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  • 1.
    Andersson, Andreas
    et al.
    Electric Propulsion Systems Department, Volvo Car Group, Gothenburg, Sweden.
    Lennström, David
    oise, Vibrations, and Harshness Department, Volvo Car Group, SE-405 31 Gothenburg.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Influence of Inverter Modulation Strategy on Electric Drive Efficiency and Perceived Sound Quality2016In: IEEE Transactions on Transportation Electrification, ISSN 2332-7782, Vol. 2, no 1, p. 24-35Article in journal (Refereed)
    Abstract [en]

    This paper presents an evaluation of differentmodulation techniques and different levels of switching frequencyrandomization for a rear axle electrical drive unit used in auto-motive applications. Inverter and machine losses, and perceivedsound quality of high-frequency acoustic noise are investigated byfinite element calculations, experimental testing, and subjectivenoise assessment. Additionally, stator current harmonics, airgapflux density harmonics, and force density harmonics are comparedfor space vector modulation (SVM) and discontinuous pulsewidthmodulation through finite element modeling. The main conclusionis that, primarily in the field weakening region, significant energysavings can be achieved (up to 17% decrease in total inverter losseswith a switching frequency of 10 kHz). This is obtained withoutdeterioration of perceived sound quality by the use of discontinu-ous pulsewidth modulation with switching frequency randomiza-tion. Furthermore, randomization of the switching frequency doesnot improve the perceived sound quality of the acoustic noise whenusing SVM. However, for discontinuous pulsewidth modulation,improvements in perceived sound quality when randomizing theswitching frequency are observed, primarily below base speed.

  • 2.
    Berg, Jan
    et al.
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Johannesson, Tomas
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Löfdahl, Magnus
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    In-ear vs. loudspeaker monitoring for live Sound and the effect on audio quality attributes and musical performance2017In: 142nd Audio Engineering Society International Convention 2017, AES 2017, 2017Conference paper (Refereed)
    Abstract [en]

    A successful performance of live music is dependent on how well musicians can hear themselves and the other members of the ensemble. Sound reinforcement systems can offer monitoring either by on-stage loudspeakers or in-ear headphones. These two monitoring conditions were compared to search for perceived auditory differences that affect parts of musical performance. Four jazz/pop/rock bands made live performances where monitor sound was provided to the musicians. Each band repeated their performance, changing from one monitoring condition to the other. After every performance, the musicians responded to questionnaires covering musical performance and audio quality. Experts also assessed recordings of the performances. Results show that perceived differences exist in audio quality and musical performance between loudspeaker monitors and in-ear headphone monitors.

  • 3.
    Ekeroot, Jonas
    et al.
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Berg, Jan
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Criticality of audio stimuli for listening tests: listening durations during a ranking task2014In: 136th Audio Engineering Society Convention 2014, Red Hook, NY: Curran Associates, Inc., 2014, p. 114-122Conference paper (Refereed)
    Abstract [en]

    The process of selecting critical audio stimuli for listening tests is known from the literature to be both labor-intensive and time-consuming, and has been described as more of art than science. Explicit accounts of systematic procedures are not the most commonly encountered. In a previous study a ranking-by-elimination method was investigated, resulting in a rank order that could be used as a guide for critical stimuli selection. This paper presents a further exploratory analysis of data on the subjects’ listening durations, both as a function of number of stimuli left on screen and individually per stimulus. A strong negative correlation was found between the rank order of criticality and playing duration.

  • 4.
    Ekeroot, Jonas
    et al.
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Berg, Jan
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Selection of audio stimuli for listening tests2011In: 130th Audio Engineering Society convention 2011: London, United Kingdom, 13 - 16 May 2011, Red Hook, NY: Curran Associates, Inc., 2011, Vol. 2, p. 1211-1217Conference paper (Refereed)
    Abstract [en]

    Two listening test methods in common use for the subjective assessment of audio quality are the ITU-R recommendations BS.1116-1 for small impairments and BS.1534-1 (MUSHRA) for intermediate quality. They stipulate the usage of only critical audio stimuli (BS.1116-1) to reveal differences among systems under test, or critical audio stimuli which represents typical audio material in a specific application context (MUSHRA). A poor selection of stimuli can cause experimental insensitivity and introduce bias, leading to inconclusive results. At the same time this selection process is time-consuming and labour-intensive, and is difficult to conduct in a systematic way. This paper reviews and discusses the selection of audio stimuli in listening test-related studies.

  • 5.
    Johnsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    A comparison of speech intelligibility in artificial head and Jecklin disc recordings2011In: 130th Audio Engineering Society convention 2011: London, United Kingdom, 13 - 16 May 2011, Red Hook, NY: Curran Associates, Inc., 2011, Vol. 2, p. 686-694Conference paper (Refereed)
    Abstract [en]

    Binaural recordings are often done using artificial heads but can also be done with a Jecklin disc. In this study an experiment was designed that allowed evaluation of noise and reverberation suppression based on speech intelligibility measurements. Recordings of a voice and disturbing noise were done in a reverberant environment using one artificial head and four Jecklin discs of various sizes. A listening experiment using headphones was conducted to determine the speech intelligibility in the recordings and in a real life situation. It was found that there was no significant difference in the speech intelligibility between the artificial head and Jecklin disc with a diameter of 36 cm.

  • 6.
    Johnsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stud noise auralization2013In: SAE technical paper series, ISSN 0148-7191, Vol. 6, no 3, p. 1577-1585Article in journal (Refereed)
    Abstract [en]

    During the winter special winter tires are used to prevent the car from slipping and the grip can be improved by using studded tires. Studded tires are known to cause higher noise levels and noise that is perceived as more annoying than non-studded tires. The objective was to model the interaction between the stud pattern and the stud/tire response (i.e. sound) caused by the excitation of the studs, and to make the result audible. In this study the interior airborne noise caused by the studs was auralized using a combination of recordings, modeling and filtering.The proposed stud auralization model makes it possible to evaluate the influence of the stud pattern and the stud/tire response at any desired speed. The noise caused by the studs is determined by the stud/tire responses when studs hit the pavement, the stud pattern and the speed of the tire. The stud patterns and the stud/tire responses were measured for 5 different studded tires. Auralizations were created for all combinations of stud patterns and responses at two different speeds. A listening test was conducted to assess the annoyance of the stud noise auralizations.From the listening test it was found that no single stud pattern or stud/tire response always performed best. There were large variations between the two auralized speeds. This implies that a stud pattern cannot be developed without taking the response of the tire into account. Auralizations must also be done and evaluated at different speeds.

  • 7. Johnsson, Roger
    et al.
    Odelius, Johan
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Self assessment of speech intelligibility listening to binaural recordings2009In: 38th International Congress and Exposition on Noise Control Engineering 2009: INTER-NOISE 2009 ; Ottawa, Canada, 23 - 26 August 2009 / [ed] J. Stuart Bolton, Red Hook, NY: Curran Associates, Inc., 2009, p. 43-51Conference paper (Refereed)
    Abstract [en]

    Our ability to focus on a talker in an environment with several talkers is improved by our binaural hearing. The ability to listen to one talker is improved if the talkers are spatially well separated. A common problem with binaural recordings is front-back confusion, which can make it more difficult to focus on the target talker among several talkers. In this study the ability to localize a talker is compared to the ability to follow a talker in situations with several talkers. In the first part the subjects were asked to localize a talker in the horizontal plane listening to binaural recordings. In the second part of the study the subjects were instructed to assess their ability to follow a target male voice in presence of a masker consisting of two voices (male and female).Target and maskers were presented through separate loudspeakers in various positions. The same listening test was also performed with binaural recordings of the test environment using different artificial heads and in-ear recordings of humans. In both parts the binaural recordings were presented to the subjects through loudspeakers using cross-talk cancellation. Correlation between localization performance and self assessed speech intelligibility was analyzed.

  • 8.
    Lennström, David
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Determination of radiated sound power from an electric rear axle drive in-situ and its contribution to interior noise2013In: SAE technical paper series, ISSN 0148-7191, Vol. 6, no 3, p. 1554-1563Article in journal (Refereed)
    Abstract [en]

    System and component target setting for noise and vibration are important activities within automotive product development. New challenges arise when electric motors are introduced into cars traditionally powered by combustion engines. The emitted noise from an electric traction motor for hybrid electric vehicles is characterized by high frequency tonal components from the dominating magnetic harmonics which can be perceived as annoying. Sound power is frequently used for quantifying the airborne noise from rotating electrical machines. This paper describes the process of determining the radiated sound power from an automobile electric rear axle drive in-situ and its contribution to interior cabin noise for a prominent rotor order. The sound power was calculated by combining the average stator surface vibration velocity together with an estimate of the radiation efficiency. To model the radiation efficiency, the vibration shape of the cylindrically shaped stator shell was determined by means of operational deflection shapes. The acoustic transfer functions between the source and receiver positions close to a passenger's ear, were defined as the ratio of sound pressure and sound power. By combining the acoustic transfer functions with the calculated operational sound power, the airborne interior noise can be predicted. The calculated interior noise levels were found to be in accordance, within approximately 3 dB, with the measured airborne noise from the stator shell. This indicated that the method is valid and could be helpful for calculating allowed radiated power from interior noise targets and acoustic transfer functions.

  • 9.
    Lennström, David
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    The influence of the acoustic transfer functions on the estimated interior noise from an electric rear axle drive2014In: SAE International Journal of Passenger Cars - Mechanical Systems, ISSN 1946-3995, E-ISSN 1946-4002, Vol. 7, no 1, p. 413-422Article in journal (Refereed)
    Abstract [en]

    In the vehicle development process, targets are defined to fulfill customers' expectations on acoustic comfort. The interior complete vehicle acoustic targets can be cascaded down to system and component targets, e.g. insulation properties and source strengths. The acoustic transfer functions (ATFs) from components radiating airborne noise play a central role for the interior sound pressure levels. For hybrid vehicles fitted with an electric traction motor, the contribution of high frequency tonal components radiated from the motor housing needs to be controlled. The interior sound pressure due to an airborne motor order can be estimated by surface velocities and ATFs. This study addresses the ATFs measured from a large number of positions located around an electric rear axle drive (ERAD) and their influence on estimated interior noise. First, the magnitude variation between the individual ATFs and how it clearly can be visualized was presented. Displaying all ATFs in a color map revealed the magnitude at each geometrical location of the respective microphone. Secondly, the influence of the ATF's spatial resolution on estimated interior sound pressure was investigated. This was done for theoretical models of the stator shell source shape and also for measured surface velocities. By reducing the spatial resolution from 0.05 to 0.10 m between each microphone, the difference in noise contribution is typically within three decibels with a 12th octave smoothing filter applied to the narrow-band data. The findings from this work provide insight in the risks of compromising with the number of ATF's needed for contribution analysis.

  • 10.
    Lennström, David
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lindbom, Thomas
    Volvo Car Corporation.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Prominence of tones in electric vehicle interior noise2013In: Internoise 2013: Noise Control for Quality of Life, Innsbruck: ÖAL Österreichischer Arbeitsring für Lärmbekämpfung , 2013, Vol. 1, p. 508-515, article id 150Conference paper (Refereed)
    Abstract [en]

    The rapid increase of various types of electric vehicles introduced creates new challenges also in respect to noise control and sound quality. With the absence of acoustic emissions from an operating internal combustion engine, the presence of high pitched tonal components from the electric traction motor can be pronounced in many driving conditions. In order to fulfill the customer’s expectations of interior acoustic comfort, further knowledge needs to be gained about the perception of tonal components appearing in a mix of random noise from wind and tires. This paper presents a study on the relationship between the psychoacoustic metric prominence ratio (PR) and the threshold of detecting the tones and also the perceived annoyance for both constant speed and acceleration in a pure electric vehicle. The listening test results reveal that below 800 Hz, a higher PR value is required for audibility compared to tones above 2.5 kHz. For all driving conditions, the perceived annoyance was relatively low with small differences between the frequency ranges for the low audibility stimuli (PR≤2 dB). With higher audibility (PR≥3 dB), the perceived annoyance was significantly increased for frequencies above 5 kHz compared to frequencies below 800 Hz for the constant speed cases. The acceleration cases yielded similar conclusions. The findings are intended to support in the requirement specification process for sounds in electric vehicles.

  • 11.
    Lennström, David
    et al.
    Volvo Car Corporation.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Interior sound of today's electric cars: Tonal content, levels and frequency distribution2015In: SAE technical paper series, ISSN 0148-7191, Vol. 2015-01-2367Article in journal (Refereed)
  • 12.
    Lennström, David
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Olsson, Magnus
    Volvo Car Corporation, Dept. 91600/PV2C2.
    Wullens, Frédéric
    Volvo Car Corporation, Dept. 91600/PV2C2.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Validation of the blocked force method for various boundary conditions for automotive source characterization2016In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 102, p. 108-119Article in journal (Refereed)
    Abstract [en]

    Vibro-acoustic source characterization is an essential task in vehicle development to enable prediction of receiver response. For structure-borne noise, the interface forces in multiple degrees of freedom due to internal loads are often quantified for root cause analyses in a single system assembly, as in transfer path analysis (TPA). However, for a reliable prognosis of the acoustic performance of a known component such as a motor or pump, a receiver-independent source characterization is required, and the method of acquiring blocked forces from in-situ measurements has been shown to be a preferred technique for such purposes. The benefits of the method are the characterization of the intrinsic properties of the source and the possibilities of measuring the component attached to receivers with varying dynamic properties.There is to date a limited number of validation cases where blocked forces from in-situ measurements are acquired for automotive source–receiver assemblies. In this study the blocked forces of a vacuum pump in nine degrees of freedom were determined when connected to a bracket whose boundary conditions were modified in order to achieve four assemblies with different source/receiver dynamic properties. The results show that the blocked forces are transferable, i.e. the receiver response in one assembly was predicted in a wide frequency range by combining source–receiver transfer functions of that assembly with blocked forces estimated in another assembly. Furthermore, an in-situ blocked force TPA was applied to a double-isolated complete vehicle source–receiver case of an electric rear axle drive with interior compartment sound pressure as target. The reconstructed magnetic tonal harmonics agreed with the measured target response in the frequency range 50–500 Hz, which further motivates the use of the blocked force principles for TPA and source requirements specifications.

  • 13.
    Lennström, David
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sound quality evaluation of electric cars: preferences and influence of the test environment2011In: Aachener Akustik Kolloquium 2011: proceedings, 2011Conference paper (Other academic)
  • 14.
    Lindegren, David
    et al.
    Ericsson Research, Sweden.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ljung, Robert
    Engineering psychology, University of Gävle.
    The AMR-NB Voice Codec Reduces the Listener’s Capacity to Recall Speech2018In: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 104, p. 381-384Article in journal (Refereed)
    Abstract [en]

    Modern telecommunication services generally use digital speech encoding. Speech encoding degrades the audio with compression and filters to make the data transmission more efficient. To keep conversations and on-line meetings productive and creative it is important that these digital services do not increase the cognitive load. Measuring effects on working memory is one way to estimate cognitive load of the listener. A test with 25 participants was performed to investigate the effects of using the AMR-NB codec, a standardized codec for mobile communication. The memory performance for spoken 12-word lists was measured and AMR-NB encoded speech was compared with unprocessed speech (LPCM 16 bit, 44.1 kHz). A within-subject analysis showed 9% lower recall rate for the AMR-NB coded speech.

  • 15.
    Lundkvist, Andre
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    3D-sound in car compartments based on loudspeaker reproduction using crosstalk cancellation2011In: 130th Audio Engineering Society convention 2011: London, United Kingdom, 13 - 16 May 2011, Red Hook, NY: Curran Associates, Inc., 2011, Vol. 1, p. 203-213Conference paper (Refereed)
    Abstract [en]

    One way to enhance driving safety is to use signal sounds. Driver attention may further be improved by placing sounds in a 3D-space, using binaural synthesis. For correct loudspeaker reproduction of binaural signals, crosstalk between the channels needs to be cancelled out. In this study, a crosstalk cancellation algorithm was developed and tested. The algorithm was applied in a car compartment, and three loudspeaker positions was compared. A listening test was performed to determine the subjects' ability to correctly localise sounds. It was shown that loudspeakers placed behind the listener correctly reproduced sound sources in the back hemisphere. Loudspeakers located in front and above the listener gave a high number of front/back confusions for all angles.

  • 16.
    Lundkvist, André
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Stridfelt, Jakob
    Luleå University of Technology.
    3D Auditory Displays for Parking Assistance Systems2017In: SAE International Journal of Passenger Cars - Electronic and Electrical Systems, ISSN 1946-4614, E-ISSN 1946-4622, Vol. 10, no 1, p. 17-23Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to investigate if 3D auditory displays could be used to enhance parking assistance systems (PAS). Objective measurements and estimations of workload were used to assess the benefits of different 3D auditory displays. In today’s cars, PAS normally use a visual display together with simple sound signals to inform drivers of obstacles in close proximity. These systems rely heavily on the visual display, as the sound does not provide information about obstacles' location. This may cause the driver to lose focus on the surroundings and reduce situational awareness. Two user studies (during summer and winter) were conducted to compare three different systems. The baseline system corresponded to a system normally found in today’s cars. The other systems were designed with a 3D auditory display, conveying information of where obstacles were located through sound. A visual display was also available. Both normal parking and parallel parking was conducted. Time taken for parking and the number of obstacles/curb hits were recorded. Participants answered a NASA TLX questionnaire after evaluating each PAS for estimation of their experienced workload. Most participants enjoyed the additional information provided by the 3D auditory displays. The winter trial showed a significant reduction in perceived effort when using a 3D auditory display compared to the baseline. The summer trial showed tendencies of higher mental demand and frustration with the baseline compared to the 3D auditory displays. The results suggest that 3D auditory displays can be appreciated and useful in difficult parking situations.

  • 17.
    Lundkvist, André
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Response Times for Visual, Auditory and Vibrotactile Directional Cues in Driver Assistance Systems2016In: SAE International Journal of Transportation Safety, ISSN 2327-5626, E-ISSN 2327-5634, Vol. 4, no 1, p. 8-14Article in journal (Refereed)
    Abstract [en]

    The number of advanced driver assistance systems is constantly increasing. Many of the systems require visual attention, and a way to reduce risks associated with inattention could be to use multisensory signals. A driver's main attention is in front of the car, but inattention to surrounding areas beside and behind the car can be a risk. Therefore, there is a need for driver assistance systems capable of directing attention to the sides. In a simulator study, combined visual, auditory and vibrotactile signals for directional attention capture were designed for use in driver assistance systems, such as blind spot information, parking assistance, collision warnings, navigation, lane departure warning etc. An experiment was conducted in order to measure the effects of the use of different sensory modalities on directional attention (left/right) in driver assistance systems. Attention was assessed in a driving simulator using Lane Change Task together with a secondary task, designed to measure choice response times and error rates to directional (left/right) information for multisensory signals. Different combinations of visual, auditory and vibrotactile signals were tested and compared. Visual signals alone (when captured by the driver) or in combination with other modalities provided shortest response times (570 ms on average). Auditory and vibrotactile signals captured attention equally well in terms of response time (650 ms and 740 ms on average). No significant differences in localization error rates were observed.

  • 18.
    Lundkvist, André
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Signal Sound Positioning Alters Driving Performance2016In: SAE International Journal of Transportation Safety, ISSN 2327-5626, E-ISSN 2327-5634, Vol. 4, no 1, p. 1-7, article id 2015-01-9152Article in journal (Refereed)
    Abstract [en]

    Many of the information systems in cars require visual attention, and a way to reduce both visual and cognitive workload could be to use sound. An experiment was designed in order to determine how driving and secondary task performance is affected by the use of information sound signals and their spatial positions. The experiment was performed in a driving simulator utilizing Lane Change Task as a driving scenario in combination with the Surrogate Reference Task as a secondary task. Two different signal sounds with different spatial positions informed the driver when a lane change should be made and when a new secondary task was presented. Driving performance was significantly improved when both signal sounds were presented in front of the driver. No significant effects on secondary task performance were found. It is recommended that signal sounds are placed in front of the driver, when possible, if the goal is to draw attention forward.

  • 19.
    Löfdahl, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    An auralization model for structure borne tyre noise based on operational data2012In: Proceedings ISMA 2012: International Conference on Noise and Vibration Engineering, Leuven: Katholieke Universitat , 2012, Vol. 2, p. 1583-1594Conference paper (Refereed)
    Abstract [en]

    Reducing development time and costs is a never ending challenge in the automotive industry. Development times are decreased by using CAE-tools for early predictions of product performances and qualities and by moving field testing to indoor lab-environments. In the automotive industry, an NVH issue such as road noise is an important factor for the perceived product quality. A useful method to address NVH problems and to reduce field testing is to combine recordings and simulations into auralizations. The objective of this study was to compare auralization of structure borne tyre noise based on operational data against artificial head recordings made under the same conditions. Results from a listening test showed that clear audible differences existed in the auralizations compared to the artificial head recordings. These audible differences were caused by low coherence in the measured binaural transfer functions below 150 Hz and in the frequency range 1000-1600 Hz.

  • 20.
    Löfdahl, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    An auralization model for structure-borne tire noise2015In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 96, p. 61-67Article in journal (Refereed)
    Abstract [en]

    In the automotive industry, a Noise, Vibration, and Harshness (NVH) issue such as road noise is an important factor for the perceived quality of a product. A useful method to address NVH problems and to reduce field-testing is to combine recordings and simulations into auralizations. The objective of this paper was to develop an auralization model of structure-borne tire noise based on operationally measured hub forces and validate it by comparison with artificial head recordings made under the same conditions. To create auralizations under the same condition as the recordings, the wheel hub forces used for the recordings were measured and filtered through experimentally measured binaural transfer functions from the same hub of the car to an artificial head in the cabin of the car. The auralization model was validated in a listening test where the criterion for considering the auralizations to be sufficiently similar to the recordings was that eight different tires should be ranked equally in a listening test regardless of whether the test was based on auralizations or recordings. Listening test results from ranking of tires with respect to the annoyance of interior sounds showed good agreement between auralizations and recordings. There were no significant differences between rankings based on recordings and auralizations – except for tires assessed to be very similar – at either 50 km/h or 70 km/h. The conclusion was that the use of auralizations for ranking of structure-borne tire noise gives results that match listening tests based on recordings, and this supports the validity of the auralization model.

  • 21.
    Löfdahl, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Mobility measurement in six DOFs applied to the hub of a car2014In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 83, p. 108-115Article in journal (Refereed)
    Abstract [en]

    Complex models are usually needed to predict functional performance of mechanical devices such as noise and vibration levels. A typical model is divided into substructures where each substructure is described either as a simulation or as an experimental model. When coupling substructures, information is needed that describes the boundary conditions at the attachment points of the various substructures. This can be hard to achieve, especially when full structural behavior including rotational degrees of freedom (DOFs) are needed. The objective of this study was to obtain the mechanical mobility matrix in six DOFs for a wheel hub of car, as an example of a complex mechanical structure, through an experimental approach based on the multiple-input multiple-output technique. Further, evaluation of the measurement quality was conducted without requirements for numerical simulation comparisons. A specially designed brake disc was fabricated for direct attachment of shakers and transducers. The quality of the 6-DOF mechanical mobility matrix was evaluated using reciprocities, coherence functions, and random error in the gain-factor estimates. The results showed good quality in the reciprocities, and the multiple coherences in each degree of freedom were close to one in the frequency range of 25–500 Hz. The random error can be reduced by increasing the number of averages.

  • 22.
    Löfdahl, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Assessment of changes in automotive sounds caused by displacements of source and listening positions2012In: Noise Control Engineering Journal, ISSN 0736-2501, E-ISSN 2168-8710, Vol. 60, no 3, p. 283-292Article in journal (Refereed)
    Abstract [en]

    Artificial head recordings are commonly used to measure and evaluate soundquality. In sound quality assessments, spatial qualities are crucial both forcorrect localization and separation of sources. Changes in locations of thesource and/or the receiver will alter the character of the sound since the binauraltransfer functions will alter. However, in complex environments (i.e. not freefield conditions) such as a car compartment, the required accuracy in positioningof sources and receivers cannot be drawn from previous studies of localizationblur. Therefore, examples of automotive sounds were reproduced through aloudspeaker in a source position outside a car and recorded with an artificialhead inside the car. Changes in perceived sound character caused by displacements of either the source or the receiver position were studied through a listening test. Just noticeable displacements were determined and perceiveddifferences compared to a reference position were rated. In addition, binauraltransmissibility functions of airborne sounds were measured and comparedwith the listening test results. The results showed that artificial head recordingsand measurements of binaural transmissibility functions were affected by smalldisplacements in location of both the source and the receiver. However, it washard to assess perceived differences from measured binaural transmissibilityfunctions. This highlights the importance of performing listening tests. Basedon this study, the recommended maximum inaccuracy in positioning of sourcesand receivers for binaural measurements in cars is 1 cm, in order to avoid audibleeffects.

  • 23.
    Löfdahl, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Measurements of variations in binaural transfer functions caused by displacements of sources and receivers2009In: 38th International Congress and Exposition on Noise Control Engineering 2009: INTER-NOISE 2009 ; Ottawa, Canada, 23 - 26 August 2009 / [ed] J. Stuart Bolton, Red Hook, NY: Curran Associates, Inc., 2009, p. 4694-4702Conference paper (Refereed)
    Abstract [en]

    Noise generated in cars is transmitted through airborne and structure borne transfer paths into the cabin. Changes in the locations of either the source or the receiver will alter the transfer path. Binaural transfer functions of airborne sound were measured in order to determine how changes in locations of either the source or the receiver affect them. The measurements were performed on a car where the binaural transfer functions for various positions of the source and the receiver were measured directly. In addition, examples of automotive sounds were reproduced through a loudspeaker in the source position and recorded with an artificial head in the receiver position. Changes in perceived sound quality caused by displacements of the source and the receiver position was studied through a listening test and compared to the changes in binaural transfer functions. The results show that the binaural transfer functions are affected by small displacements in location for either the source or the receiver. This variability causes changes in sound quality and must be considered in order to draw correct conclusions from transfer function measurements and sound quality analyses based on artificial head recordings.

  • 24.
    Löfdahl, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Prominence of Different Directions of Hub Forces and Moments in Structure-Borne Tire Noise2015In: SAE International Journal of Passenger Cars - Mechanical Systems, ISSN 1946-3995, E-ISSN 1946-4002, Vol. 8, no 1, p. 346-353, article id 2015-01-9106Article in journal (Refereed)
    Abstract [en]

    In the automotive industry, tire noise is an important factor for the perceived quality of a product. A useful method to address such NVH problems is to combine recordings with measurements and/or simulations into auralizations. An example of a method to create structure-borne tire noise auralizations is to filter recordings of hub forces and moments through binaural transfer functions experimentally measured from the hub of the car to an artificial head in the car cabin. To create authentic auralizations of structure-borne sound, all six degrees of freedom (DOFs) of hub forces and moments and transfer functions should be included. However, rotational DOFs are often omitted due to measurement difficulty, complexity, time, and cost. The objective was to find which DOF (or DOFs) is perceived as most prominent in structure-borne tire noise. An auralization model of interior structure-borne tire noise was used. An auralization including all DOFs was compared with auralizations lacking one DOF at a time in a listening test. Auralizations lacking either all translational DOFs or all rotational DOFs were also included. Results from the listening test showed that the overturning moment (Mα) was perceived as the most prominent DOF. Removing all rotational DOFs led to a larger audible difference than removing all translational DOFs. Therefore, rotational DOFs should not be disregarded in tire noise auralization. The results suggest which DOFs are important to consider in tire and vehicle sound design.

  • 25.
    Normark, Carl Jörgen
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Tretten, Phillip
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Grane, Camilla
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundkvist, Andre
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Project: Human Factors LAB2014Other (Other (popular science, discussion, etc.))
  • 26.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Methods for product sound design2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Product sound design has received much attention in recent years. This has created a need to develop and validate tools for developing product sound specifications. Elicitation of verbal attributes, identification of salient perceptual dimensions, modelling of perceptual dimensions as functions of psychoacoustic metrics and reliable auralisations are tools described in this thesis. Psychoacoustic metrics like loudness, sharpness and roughness, and combinations of such metrics into more sophisticated models like annoyance, pleasantness and powerfulness are commonly used for analysis and prediction of product sound quality. However, problems arise when sounds from several sources are analysed. The reason for this complication is assumed to be the human ability to separate sounds from different sources and consciously or unconsciously focus on some of them. The objective of this thesis was to develop and validate methods for product sound design applicable for sounds composed of several sources. The thesis is based on five papers. First, two case studies where psychoacoustic models were used to specify sound quality of saxophones and power windows in motor cars. Similar procedures were applied in these two studies which consisted of elicitation of verbal attributes, identification of most salient perceptual dimensions and modelling of perceptual dimensions as functions of psychoacoustic metrics. In the saxophone experiment, psychoacoustic models for prediction of prominent perceptual qualities were developed and validated. The power window experiment showed that subjects may judge only parts of the sound. Power window sound consists of the motor sound and the scratching of a window sliding over the seal. The motor sound was filtered out and models developed using motor sound alone showed good agreement with listening tests. This demonstrated the human ability to separate sound from different sources and pointed out the importance of handling auditory stream segregation in the product sound design process. In Paper III sound sketches (simple auralisations) was evaluated as a way to assess sounds composed of several sources. Auralisation allows control of the contributions of different sources to a sound at the listening position. This way, psychoacoustic analysis and listening tests may be carried out on the contributions from sources separately and as an ensemble. Sound sketches may also serve to specify a target sound for a product. In Papers IV and V, the precision of auralisations related to intended use was investigated. Auralisations were made by filtering engine sounds through binaural transfer functions from source locations to the listening position in a truck cabin. In Paper IV simplifications of auralisations of one source were compared to artificial head recordings. For idling sounds auralisations through binaural transfer functions with a resolution of 4 Hz or better, or smoothed with maximum 1/96 octave moving average filters were found to preserve perceived similarity to artificial head recordings. In Paper V the effect of simplifications of transfer functions on preference ratings of auralisations was examined. This is of interest in applications where audible differences may be acceptable as long as preference ratings are unaltered, e.g. when auralisations are used as rough sound sketches. At 500 rpm idle speed, a resolution of 32 Hz or better, or smoothing with maximum 1/24 octave moving average filters showed no significant alteration of subject preference ratings. These figures may serve as guide for required accuracy in auralisations used for evaluation of idling sounds in truck cabins. To conclude, psychoacoustic analysis of total sound may be used for prediction of perceived sound quality as long as the sound is generated by one source. When several sources generate sound, auditory stream segregation effects in combination with cognitive effects may deteriorate the results. Auralisation is a useful tool in such cases, since it makes it possible to analyse the effects of contributions from each source. It can also be used for making sound sketches which can serve as support in the design process.

  • 27.
    Nykänen, Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Methods for specification of sound quality applied to saxophone sound2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Product specifications that include descriptors of sound qualities are most helpful when a description contains adequate detail and utilises understandable wording. Good specifications require that any descriptions used are familiar to users and that these descriptions are interpretable as acoustical quantities. The objectives of the studies reported upon in this thesis were to investigate how musicians use verbal descriptions of musical sounds and to interpret the descriptions in terms of some commonly used acoustical quantities. Interviews were made with saxophone players and the results were analysed with respect to how frequently different words were used. The most frequently used words were evaluated through listening tests using binaurally recorded test sounds of two saxophone players playing on two saxophones of different brands. Two groups of subjects participated in the listening tests, saxophone players and non-saxophone players. The subjects were asked to judge how well words selected from the interviews described the timbre of the test sounds. Data from the listening tests was analysed to examine how 3 factors: musician, saxophone, and type of listener influenced subject judgements. Principal Component Analysis (PCA) was used to find the most significant perceptual dimensions for the test sounds. Results from factorial analysis of variance and PCA were used to select the most appropriate verbal descriptions that best described significant perceptual dimensions. A small set of words (9 words) suitable for describing the variations in the analysed sounds was developed. To interpret the perceptual dimensions in terms of physically measurable indices, a number of acoustical quantities were added one by one to the set of perceptual variables. PCA of these extended data sets, resulted in a suggestion as to how the perceptual dimensions could be defined in terms of acoustical quantities. The procedure resulted in two significant perceptual dimensions being developed and described. A bipolar scale was used to describe Dimension 1 where items on the scale ranged from sharp/keen/rough to soft/warm/full-toned. Dimension 2 was described by a unipolar scale using the term E-like. The acoustical quantities sharpness, tonality, loudness, specific roughness (5-6 Bark and 21-22 Bark) and specific loudness (8-14 Bark) correlated with sharp/keen/rough. Roughness and specific roughness (13- 14 Bark and 20-21 Bark) correlated with soft/warm/full-toned. Specific loudness (10-11 Bark ) correlated negatively with E-like/large and specific loudness (9-10 Bark) and specific roughness (7-9 Bark) correlated positively with E-like/large. These findings demonstrate that it is possible to subjectively describe sound quality and to relate acoustical quantities to the descriptions. This suggests that it is practical to develop sound description terminology useful for work such as preparation of specifications and subsequent product standardisation.

  • 28.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Örjan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Design of product sound by blending of sound sources2007In: The 19th International Congress on Acoustics, ICA 2007 : Madrid: Acoustics for the 21st century / [ed] Antonio Calvo-Manzano, Madrid: Spanish Acoustical Society , 2007Conference paper (Refereed)
    Abstract [en]

    Product sound usually consists of a mix of several sources. Models for prediction of sound quality based on combinations of psychoacoustic metrics like loudness, sharpness and roughness have limitations when compound sounds are analysed. When a compound sound is divided into separable sources through auditory streaming such models fail. The character of each source is given by physical properties. The character is usually hard to change without complete redesign of the product. The quality of the final product sound is determined by the mix of sound sources. Efficient product sound design requires tools for recording or simulation of sources, realistic modelling of transfer functions from source to listener and tools for mixing the sources. With such tools a sound source can be auralised as part of sound environments. Recordings of sound sources in a car were used to get source information. The sound from each source was filtered through idealised transfer functions, mixed and reproduced in a 5.1 surround sound studio. The resulting sound was evaluated through listening tests. This approach was shown to be a powerful tool for evaluation of the effect of auditory streaming on subjective judgments of compound product sound.

  • 29.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Örjan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Development of a language for specifying saxophone timbre2003In: Proceedings of SMAC 03: Stockholm Music Acoustics Conference, August 6-9, 2003. / [ed] Roberto Bresin, Stockholm: Kungl. Tekniska Högskolan , 2003, Vol. 2, p. 647-650Conference paper (Refereed)
  • 30.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Örjan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Berg, Jan
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Modelling perceptual dimensions of saxophone sounds2009In: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 95, no 3, p. 539-549Article in journal (Refereed)
    Abstract [en]

    In the past, musical instruments were developed over long periods of time by skilled craftsmen. Today, most instruments are mass-produced. Design of musical instruments as mass-produced products requires using strategies which make it easier to identify customer needs and develop exact specifications. To develop useful specifications it is necessary to convert general descriptions into something which can be commonly understood and also be interpretable in terms of acoustic metrics. In this study, methods for analysis and specification of steady state parts of alto saxophone sounds were developed. Saxophonists' use of verbal descriptions of saxophone sounds was investigated. Sound stimuli were binaurally recorded. Judgements upon perceived qualities were made by saxophonists and non-saxophonists using the method of verbal attribute magnitude estimation. Perceptual dimensions were identified using principal component analysis of listening test data. Three prominent dimensions were found and described using the verbal attributes: 1) warm/soft, 2) back vowel analogues and 3) sharp/rough. The perceptual dimensions were modelled as linear functions of acoustic metrics. The results were validated through listening tests with new subjects and new stimuli. Based on the findings, the method was seen as an approach which can enhance the musical instrument design process.

  • 31.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Örjan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Berg, Jan
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Perceptual and acoustical dimensions of saxophone sound2005In: Forum Acusticum Budapest 2005, 4th European Congress on Acoustics: 29 August - 2 September 2005, Budapest, Hungary, 2005, p. 519-524Conference paper (Refereed)
    Abstract [en]

    Specifications of product sound qualities may contain both perceptual and acoustical descriptions. The perceptual descriptions are most helpful when they contain adequate detail and utilises understandable wording. To facilitate the product design process the descriptions should also be interpretable as acoustical quantities. The objectives of the study reported upon here were to investigate how musicians use verbal descriptions of sound and to interpret these descriptions in terms of commonly used acoustical quantities. Musicians' use of verbal descriptions of saxophone sound was investigated through interviews. The most frequently used words were evaluated through listening tests. The subjects were asked to judge how well the words described the timbre of test sounds. To find the most significant perceptual dimensions for the test sounds Principal Component Analysis was used. Four significant dimensions were found and described by 9 words. To interpret the perceptual dimensions in terms of physically measurable indices, models for how acoustical quantities relate to the perceptual dimensions were developed. Dimension 1 was described by full-toned/warm/soft. The psycho-acoustical quantity sharpness correlated negatively with this dimension. Dimension 2 was described by the term [o]-like. Sharpness and specific roughness (9-11 Bark) correlated negatively with this dimension. Dimension 3 was described by sharp/keen/rough. Sharpness and roughness correlated with this dimension. Dimension 4 was described by the term [e]-like. No model for prediction of this dimension was found. To validate the models the effect of a changed design of the tone holes of a saxophone was predicted with the model and validated with new listening tests.

  • 32.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    A comparison of speech intelligibility for in-ear and artificial head recordings2011In: 130th Audio Engineering Society convention 2011: London, United Kingdom, 13 - 16 May 2011, Red Hook, NY: Curran Associates, Inc., 2011, Vol. 2, p. 695-702Conference paper (Refereed)
    Abstract [en]

    Good binaural reproductions should allow the listener to suppress noise and reverberation as when listening in real life. An experiment was designed where room properties and reproduction techniques were varied in a way that allowed evaluation of noise and reverberation suppression based on speech intelligibility measurements. Artificial head recordings were compared to in-ear recordings and real life listening. Artificial head recordings were found to be equivalent to real life listening. The speech intelligibility for in-ear recordings surpassed real life listening. A possible explanation may be inaccurate equalization. The equalization is critical for correct reproduction of binaural cues. The procedure used is convenient for validation of the performance of recording and reproduction equipment intended for sound quality studies

  • 33.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Löfdahl, Magnus
    Examination of the variability between artificial head recordings made in different cars of the same brand and model2009In: 38th International Congress and Exposition on Noise Control Engineering 2009: INTER-NOISE 2009 ; Ottawa, Canada, 23 - 26 August 2009 / [ed] J. Stuart Bolton, Red Hook, NY: Curran Associates, Inc., 2009, p. 4687-4693Conference paper (Refereed)
    Abstract [en]

    Artificial heads are commonly used for the recording of samples intended for sound quality evaluations. When results from listening tests and psychoacoustic analyses shall be compared it is important to be aware of the variability between measurements made under similar conditions. To study this kind of variability, the interior sounds of five passenger cars of the same brand, model and production year were recorded binaurally. The recordings were made using two different artificial heads (Head Acoustics HMS I and HMS III) and a binaural microphone headset (Head Acoustics BHM). The recordings were made at constant speed on a test track with controlled surface roughness. Based on the recordings loudness, sharpness, roughness and annoyance were judged in a listening test. The results show how the sound quality can be expected to vary between specimen of cars of the same brand and model. This observed variability was compared to the accuracy of the three different binaural microphones used.

  • 34.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sirkka, Anna
    Interactive Institute – Sonic Studio, Piteå.
    Johansson, Örjan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Assessment of changes in preference ratings of auralized engine sounds caused by changes in frequency resolution of transfer functions2013In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 74, no 12, p. 1343-1353Article in journal (Refereed)
    Abstract [en]

    Auralization facilitates aural examination of contributions from different sound sources, individually and as parts of a context. Auralizations can be created by filtering sounds of perceptually salient sources through binaural transfer functions (BTFs) from source positions to a listening position. When such auralizations are used for product sound design it is essential to know that they are of sufficient quality. A basic requirement is that preference ratings are unaffected by the quality of the auralizations. The objective of this study was to measure changes in preference ratings of auralized engine sounds caused by changes in frequency resolution of used BTFs. Auralizations of engine sounds were created by filtering source sounds through BTFs measured from source positions to a driver’s position inside a truck cabin. The BTFs were altered by lowering the frequency resolution and by smoothing in the frequency domain. Preferences for the auralizations were compared using a modified version of the MUlti Stimulus test with Hidden Reference and Anchor, MUSHRA (ITU-R BS.1534-1). Since the use of a reference is only appropriate when a reference known to be most preferred exists the reference was removed, resulting in a MUlti Stimulus Test with Hidden Anchors (MUSTHA). For assessment of the differences between the auralizations a statistical method commonly used for assessing agreement between methods of clinical measurement was adopted. The lowest frequency resolutions resulting in acceptable agreement between preference ratings of auralizations made with high frequency resolution (1 Hz) BTFs and auralizations made with simplified BTFs were 32 Hz frequency resolution or smoothing with either 1/24 octave bandwidth filters or 63 Hz absolute bandwidth filters.

  • 35.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sirkka, Anna
    Scania, RTRN Acoustics, Truck Development.
    Johansson, Örjan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Assessment of the change in similarity judgements of auralized engine sounds caused by changes in frequency resolution of transfer functions2011In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 72, no 2-3, p. 115-123Article in journal (Refereed)
    Abstract [en]

    Auralization facilitates aural examination of contributions from different sound sources, individually and as parts of a context. Auralizations can be created by filtering sounds of the perceptually most salient sources through binaural transfer functions (BTFs) from source positions to a listening position. When psychoacoustic analysis is based on auralizations, the auralizations need to give the same impression as real sounds. The objective of this study was to determine the frequency resolution required for auralizations to be perceptually equivalent to recordings made with an artificial head. Auralizations of the contribution of engine sounds to interior sounds of a truck were examined. In listening tests auralizations based on simplified BTFs were compared to artificial head recordings. The BTFs were simplified by lowering the frequency resolution and by smoothing in the frequency domain. Auralizations made through BTFs with a resolution of 4 Hz or higher or smoothed with maximum 1/96 octave moving average filters were perceived as similar to artificial head recordings.

  • 36.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lennström, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Car Ride Before Entering the Lab Increases Precision in Listening Tests2015In: SAE International Journal of Passenger Cars - Mechanical Systems, ISSN 1946-3995, E-ISSN 1946-4002, Vol. 8, no 3, p. 982-988Article in journal (Refereed)
    Abstract [en]

    Subjects who are well aware of what to judge commonly yield more consistent results in laboratory listening tests. This awareness may be raised by explicit instructions and training. However, too explicit instructions or use of only trained subjects may direct experiment results in an undesired way. An alternative is to give fairly open instructions to untrained subjects, but give the subjects a chance to get familiar with the product and context by, for example, riding a representative car under representative driving conditions before entering the laboratory. In this study, sound quality assessments of interior sounds of cars made by two groups were compared. In one group subjects were exposed to the same driving conditions that were later assessed in a laboratory listening test by taking them on a ride in one of the cars to be assessed, just before entering the laboratory. In the other group subjects made the laboratory assessments without prior car riding. In the laboratory, sound quality was assessed for binaurally recorded interior sounds of cars reproduced through headphones. The results showed that even though average sound quality assessments in most cases were the same for both groups, the variances were significantly smaller for the group where subjects had been taken on the car ride before the listening test. A conclusion is that being exposed to the sounds in the right context just before the listening test, e.g. by riding a representative car under representative driving conditions, can increase the precision in laboratory sound quality assessments.

  • 37.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lindegren, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Wruck, Louisa
    Ljung, Robert
    University of Gävle.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Möller, Sebastian
    TU Berlin.
    Memory of AMR coded speech distorted by packet loss2014Conference paper (Refereed)
    Abstract [en]

    Previous studies have shown that free recall of spoken word lists is impaired if the speech is presented in background noise, even if the signal-to-noise ratio is kept at a level allowing full word identification. The objective of this study was to examine recall rates for word lists presented in noise and word lists coded by an AMR (Adaptive Multi Rate) telephone codec distorted by packet loss. Twenty subjects performed a word recall test. Word lists consisting of ten words were played to the subjects. The subjects repeated each word immediately after it had been played, to ensure that the words were heard correctly. After the complete list had been played the subjects wrote down all words remembered. In this way, both word identification and recall rates were measured. Three distorted conditions were compared with an undistorted control condition using a within-subject design: speech spectrum weighted noise at 4 dB SNR, and AMR coded speech with two levels of packet loss, one mild and one severe. The results confirmed the disruptive effect of noise on free recall of words, while no significant impairment was found for the AMR distortions. The noise and the AMR coding with mild packet loss gave approximately the same impairment of word identification. The AMR coding with severe packet loss gave a larger impairment of word identification, even though the word recall rate was unaffected. This result suggests that packet loss in AMR coded speech causes distortions which disrupt recall of words less than noise at levels resulting in the same change of word identification rates. Since impairment of word identification rates did not correlate with impairment of word recall rates models for quality prediction of speech reproductions should not be based on identification rates alone.

  • 38.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lopez, Mariana
    Anglia Ruskin University.
    Toulson, Rob
    Anglia Ruskin University.
    Safe and Sound Drive: Design of Interactive Sounds Supporting Energy Efficient Behaviour2016In: Proceedings of the Interactive Audio Systems Symposium, September 23rd 2016, York: Audio Lab, The Department of Electronics, The University of York, 2016Conference paper (Refereed)
  • 39.
    Nykänen, Arne
    et al.
    Cultures of Digital Economy Research Institute, Anglia Ruskin University, Cambridge.
    Lundkvist, André
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lindberg, Stefan
    Interactive Institute, Piteå.
    Lopez, Mariana
    Cultures of Digital Economy Research Institute, Anglia Ruskin University, Cambridge.
    Safe and Sound Drive: Sound Based Gamification of User Interfaces in Cars2016In: Proceedings of the AES International Conference / [ed] Spriet A.,Murphy D.,Goetze S, 2016Conference paper (Refereed)
    Abstract [en]

    The Safe and Sound Drive project concerns the design of an audio-only serious game for cars that will help drivers to increase eco-driving skills, lower fuel consumption and encourage safe and environmentally friendly approaches to driving. Methods and procedures for the design of sounds for audio-only user interfaces are reviewed and discussed, and design work and preliminary results from user studies of prototypes of the audio interface are presented. Contextual Inquiry Interviews with three participants using the audio interface in a car while driving on a test track showed that opinions about beeps and audio signals vary among subjects. Music and podcast based contents were generally well received. Alteration of media content, e.g. by actively adjusting BPM, volume, spectral balance, or music mix could form working mechanisms for providing game related cues to the driver.

  • 40.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Löfdahl, Magnus
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johannesson, Tomas
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Berg, Jan
    Luleå University of Technology, Department of Arts, Communication and Education, Media, audio technology and experience production and theater.
    Do In-ear monitors protect musicians' hearing?2017In: 142nd Audio Engineering Society International Convention 2017, AES 2017, 2017Conference paper (Refereed)
    Abstract [en]

    In-ear monitors for live performances are commonly considered to give better sound quality than loudspeaker monitors. They are also often assumed to reduce sound exposure. Because of lack of evidence for this, sound exposure for pop/rock/jazz musicians was compared between performances with in-ear and loudspeaker monitors. Equivalent sound pressure levels at the musicians' ears were 94 to 105 dBA with loudspeaker and 86 to 108 dBA with in-ear monitors. Many participants used earplugs when using loudspeaker monitors. Therefore, the recommendation, from a pure hearing protection perspective, is to use loudspeaker monitors and earplugs. However, the large spread in levels between musicians using in-ear monitors suggests that with better training and measurements of sound exposure, in-ear monitors could be used safely.

  • 41.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sirkka, Anna
    Scania, Södertälje.
    Specification of component sound quality applied to automobile power windows2009In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 70, no 6, p. 813-820Article in journal (Refereed)
    Abstract [en]

    As cars become quieter the sound quality of components with electric motors becomes more important in the customer perception of vehicle quality. This has created a need to develop methods for the specification of component sounds. The objectives of this study were to identify perceptually important aspects, link them to acoustic metrics and, based on this, develop guidelines for the determination of requirements for power window sound. Seven prominent attributes were identified: dull, loud, annoying, steady, powerful, overall product quality and under-dimensioned. Effects of auditory stream segregation influenced the results. Power window sounds mainly consist of two sources: motor and window seal scratching. Subjects tended to judge only motor sound. Prediction models developed on isolated motor sound correlated well with judgements. Low loudness, sharpness and motor speed fluctuations led to perceived high product quality. The results emphasise the importance of handling auditory stream segregation and temporal variations in the sound design process.

  • 42.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Wingstedt, Johnny
    Dalarna University.
    Sundhage, Johan
    Mohlin, Peter
    Semcon AB.
    Sketching Sounds – listening, moving and listening again2014Conference paper (Refereed)
    Abstract [en]

    Industrial design covers design of products taking all senses into account. However, most literature on product design focuses on vision. When designing multisensory human-machine interfaces tools and processes for design of sounds are needed. Sketching is essential in design. Schon and Wiggins discussed designers’ use of sketching and suggested that designers interact with the medium (typically pen and paper) in a seeing – moving – seeing way of working. First, the designer sketch to see a problem, then tries a solution by changing the sketch or suggesting a new sketch, and finally evaluates the solution by visual inspection. We suggest that design of sounds evolves through a similar process requiring the designer to listen, move and listen again. This process is facilitated by considering sounds created throughout the process as sketches. A case was studied where six designers were given the task to design a sound logotype for a car. Their processes were analyzed and compared with actions in visual sketching using pen and paper. The results support the idea of considering sound design as a listening – moving – listening process. Designing of sounds is a conversation with sounding material and crucially dependent on listening. By encouraging sound designers to use sounds as sketches during the design process creativity and efficiency were promoted.

  • 43.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Wingstedt, Johnny
    Dalarna University, Sound and Music Production, Dalarna University.
    Sundhage, Johan
    Klevgränd Produktion, Klevgränd 1B, 116 46 Stockholm.
    Mohlin, Peter
    Semcon AB.
    Sketching Sounds: listening, moving and listening again2015In: Design Studies, ISSN 0142-694X, E-ISSN 1872-6909, Vol. 39, p. 19-47Article in journal (Refereed)
    Abstract [en]

    In this work, the use of sketching in sound design was studied. Based on Schon and Wiggins' model of how designers use sketching to see, move, and see again, we suggest that sound design evolves through a similar process requiring listening, moving, and listening again. This is facilitated by considering sounds as sketches. A case was followed in which six designers were asked to design a sound logotype. Processes and interactions were studied. The results suggest that sound design can be considered as a listen – move – listen process. Sound design is a conversation with sounding material, crucially dependent on listening. To assist in this, a computer interface was developed. Analysis of its use suggests that it supported co-designing.

  • 44.
    Nykänen, Arne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Zedigh, Axel
    Semcon.
    Mohlin, Peter
    Semcon.
    Effects on localization performance from moving the sources in binaural reproductions2013In: Internoise 2013: Noise Control for Quality of Life, Innsbruck: ÖAL Österreichischer Arbeitsring für Lärmbekämpfung , 2013, Vol. 4, p. 3193-3201Conference paper (Refereed)
    Abstract [en]

    A well-known problem for reproductions of binaural recordings and simulations using HRTFs other than those of the actual listener is decreased localization performance and increased front-back confusion. Previous studies have indicated that moving the sound source can reduce these problems. The objective of this study was to measure how a unidirectional sound source movement along an orbit in the horizontal plane (achieved by reproducing sounds with a loudspeaker and turning a recording artificial head with a velocity of 5°/s) affects front-back confusion and localization errors. Two factors were studied: 1. Movement (static or rotation). 2. Acoustic environment (anechoic or reverberant). Male speech and recurring 840 Hz sinusoidal tones with a Gaussian envelope were used as stimuli. Listening tests showed that the front-back confusion rate and the rate of incorrectly perceiving that the sound is coming straight from the side were significantly lower (95% confidence level) in the reverberant condition compared to the anechoic condition. The front-back confusion rate was lower for the moving auditory scene compared to the static auditory scene, both in anechoic and reverberant conditions, but these differences were not significant. To conclude, there is reason to add room reflections to 3D sound synthesis in order to enhance localization performance in auditory displays. The effect of adding movements is small in comparison to the effect of adding reflections.

  • 45.
    Vasiliauskas, Gediminas
    et al.
    Lithuanian University of Agriculture.
    Nykänen, Arne
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Speech intelligibility in binaural reproductions compared to real life listening2010In: Sound quality evaluation: the proceedings of the AES 38th International Conference : June 13-15, 2010, Piteå, Sweden / [ed] Jan Berg, New York: Audio Engineering Society, Inc., 2010, p. 60-67Conference paper (Refereed)
    Abstract [en]

    A good reproduction of speech should allow the listener to suppress noise and reverberation as if the sounds were heard in real life. An experiment was designed where room properties and reproduction techniques were varied in a way that allowed evaluation of noise and reverberation suppression based on speech intelligibility measurements. Speech intelligibility was considerably better in real life compared to artificial head recordings presented through headphones. The headphone reproductions did not provide enough information to allow the listener to suppress noise and reverberation as well as in real life. It was found that subjects were very consistent. This makes the method precise and it should be useable for making comparisons of different reproduction techniques.

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