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  • 1.
    Asplund, Matthias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Rantatalo, Matti
    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.
    Hiensch, Martin
    Combating curve squeal noise2016In: Combating curve squeal noise, 2016Conference paper (Refereed)
    Abstract [en]

    Society demand for more sustainable transports is increasing, starting a modal shift from road to railway. The resulting increase in railway traffic intensity is leading to more activities on the track, even during the night time. For many years continuous urbanization has been resulting in a higher density of residents in areas close to railway tracks. The combination of these factors is raising the issue of noise disturbances from railway transports, which is forcing infrastructure managers to take action to combat noise from railway traffic systematically. There are different types of noise emanating from railways and one of the most annoying is curve squeal noise. This paper deals with the curve squeal phenomenon, the places where it occurs, and different methods for reducing it. The curving behaviour of a vehicle plays an important role in the generation of curve squeals, and therefore the way in which different rail profiles affect the capability to steer in a sharp curve is dealt within this paper. The paper is based on two case studies with investigated curves in urban regions that suffer from squeal noise, and in which comparisons between measurements and simulations were performed. The outcome of these studies is a workflow for combating squeal noise, results concerning the effects of a top-of-rail friction modifier on noise mitigation, and a proposed rail profiles for improving the steering capability of vehicles.

  • 2. Johansson, Örjan
    et al.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sound intensity measurements of transient noise in presence of extraneous noise2003In: Inter-Noise 2003, the 32nd International Congress and Exposition on Noise Control Engineering: August 25 - 28, 2003, International Convention Center Jeju, Seogwipo, Korea, Seoul: International institute of noise control engineering , 2003Conference paper (Refereed)
  • 3.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Crankshaft speed measurements and analysis for control and diagnostics of diesel engines2001Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The increasing demands from governments on the engine manufactures to lower the fuel consumption, lower the exhaust emissions and to reduce the noise have lead to an intensive research in the combustion process. Measurement of the combustion process inside the cylinder is only suitable in laboratory environment due to a number of limitations; the pressure transducer needed to measure the pressure is expensive, difficult to mount in the cylinder and has a limited lifetime that is much shorter than the engine's lifetime. Demands of on-board diagnostics where the combustion process is continuously monitored, on production vehicles have created a need for a method to indirectly measure the combustion process. The two main indirect methods are vibration measurement based reconstruction and crankshaft angular speed measurement reconstruction. The combustion process give rise to vibrations in the engine body that in the former method is measured with an accelerometer and the pressure can be reconstructed by using inverted transfer functions. The idea behind the latter method, the crankshaft angular speed reconstruction method, is that when one cylinder fires the produced torque is higher than the load torque and the crankshaft accelerates. As next cylinder goes into compression the total load torque increases and the crankshaft speed will decrease. This is repeated when the next cylinder fires and the produced crankshaft speed fluctuations will then contain information about the combustion and compression that caused it. In this thesis an indirect method to predict the maximum cylinder pressure is developed based on the crankshaft speed fluctuations combined with neural networks. The speed fluctuations were measured on a 6-cylinder inline diesel engine at 9 speed-load-combinations. A two layer (one hidden and one output layer) feedforward neural network was trained with the backpropagation algorithm. The prediction accuracy for pmax was found to be better than ±5 % at 95%-confidence interval for the validation set. Another important parameter for the engine control and for optimising the fuel efficiency at the same time as the exhaust emissions are kept to a minimum, is the position of the pistons most upper position, TDC (top dead centre). The TDC position is normally measured mechanically with means that need access to the cylinders (the cylinder head has to be removed). This method is time consuming and therefore expensive and because of that not used on production engines. Several indirect methods to measure the TDC- positions have been suggested. Either based on measured cylinder pressures, that again need a pressure transducer mounted in the cylinder, or on the crankshaft speed fluctuations. An indirect method based on the speed fluctuations, that are measured when the starter motor rotates the engine with turned off ignition, is developed. From the measured crankshaft speed fluctuations the TDC-positions can be determined either by curve fitting or with neural networks. The TDC position determined by curve fitting has a bias error, due to the out-of-phase acceleration component in the crankshaft that are induced by the starter motor, but also caused by heat exchange between the compressed gas and the cylinder walls and gas. The results from the neural network were found to be better and the TDC-position for all 6 cylinders was determined within ±0.1 degree crank angle at 95%-confidence interval.

  • 4.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Cylinder pressure reconstruction based on complex radial basis function networks from vibration and speed signals2006In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 20, no 8, 1923-1940 p.Article in journal (Refereed)
    Abstract [en]

    Methods to measure and monitor the cylinder pressure in internal combustion engines can contribute to reduced fuel consumption, noise and exhaust emissions. As direct measurements of the cylinder pressure are expensive and not suitable for measurements in vehicles on the road indirect methods which measure cylinder pressure have great potential value. In this paper, a non-linear model based on complex radial basis function (RBF) networks is proposed for the reconstruction of in-cylinder pressure pulse waveforms. Input to the network is the Fourier transforms of both engine structure vibration and crankshaft speed fluctuation. The primary reason for the use of Fourier transforms is that different frequency regions of the signals are used for the reconstruction process. This approach also makes it easier to reduce the amount of information that is used as input to the RBF network. The complex RBF network was applied to measurements from a 6-cylinder ethanol powered diesel engine over a wide range of running conditions. Prediction accuracy was validated by comparing a number of parameters between the measured and predicted cylinder pressure waveform such as maximum pressure, maximum rate of pressure rise and indicated mean effective pressure. The performance of the network was also evaluated for a number of untrained running conditions that differ both in speed and load from the trained ones. The results for the validation set were comparable to the trained conditions.

  • 5.
    Johnsson, Roger
    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.
    Sensitivity analysis of transfer function estimation in inverse methods2005In: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, no Suppl 1, S16- p.Article in journal (Refereed)
    Abstract [en]

    Summary form only given. A complex sound source consists of several partial sound sources that all contribute to the total sound pressure. A method to separate these partial sound sources into separate time histories is based on inverse filtering of reciprocally measured transfer functions. The transfer functions are measured reciprocally between a number of fictitious monopoles on each partial source and measurement points distributed around the sound source. The method is divided into 5 steps: recording of sound pressure signals, measurement of transfer function, calculation of source strength matrix, calculation of filters and filtering of the recorded sound pressure signals. Correct estimations of the transfer functions are critical for inverse methods to work satisfactory. Normally the transfer functions in this case of studies are calculated as H1 because of the noise contribution to the responses. However, it has been suggested that inverse methods could benefit of using H2 instead. The objective of this investigation is to analyze the effect of selecting either H1 or H2 for the calculation of the transfer functions in case of auralization of separated time histories. For the experiments a complex sound source consisting of two separate cylinder heads with valve covers have been used. Each cylinder head with valve cover was treated as a partial source. The two partial sources were excited with two uncorrelated signals that could be controlled individually. By that, listening tests could be used to verify the authenticity of the separated source signals depending of the transfer functions were estimated as H1 or H2

  • 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.
    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, 686-694 p.Conference 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.

  • 7.
    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, 1577-1585 p.Article 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.

  • 8.
    Johnsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Methods for road texture estimation using vehicle measurements2012In: Proceedings ISMA 2012: International Conference on Noise and Vibration Engineering : including USD2012 : Leuven, 17 - 19 September 2010, Leuven: Katholieke Universitat , 2012, 1573-1582 p.Conference paper (Refereed)
  • 9. 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, 43-51 p.Conference 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.

  • 10.
    Johnsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    A new test track for automotive squeak and rattle (S&R) detection2014In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 80, 79-85 p.Article in journal (Refereed)
    Abstract [en]

    The perceived quality of interior sounds is of increasing importance in the automotive industry since it is important for the customer perception of vehicle quality. Squeak and rattle (S&R) is a group of intermittent interior noise that reduce the sense of quality dramatically. To identify and solve S&R problems the car manufacturers do both simulations and tests in laboratory of complete vehicles as well as subsystems. As a complement, to laboratory testing and for verification, complete vehicle tests at proving grounds are done. In order to systematically test for vehicle S&R noise at proving grounds there is a need for a new type of test track that in a controlled and repetitive ways excite vehicles at different frequencies. This paper describes such a new test track, called the Frequency Sweep Test Track (FSTT). The test track is based on sweep excitation and improves the precision when detecting and solving S&R issues. Different design considerations such as sweep waveform, frequency range and sweep rate are discussed. The track design is evaluated using a quarter-car model including a tandem ellipsoid tyre model. In a case study a FSTT was built and the excitation of a car was measured. The track excited the expected frequency range and the track operated well in detecting a rattle in the dashboard of an executive production car and at which frequency the rattle occurred.

  • 11. Johnsson, Roger
    et al.
    Tingvall, Bror
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Predicitng interior factory noise with ray-tracing modelling: an example of hardening plant2000In: Proceedings: Inter.Noise 2000 : August 27 - 30, 2000, Nice, France / [ed] Didier Cassereau, Paris: SFA , 2000, 1595-1599 p.Conference paper (Refereed)
  • 12. Johnsson, Roger
    et al.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Cylinder pressure reconstruction from vibration and speed measurements on IC engines2004In: Noise and vibration engineering: proceedings of ISMA 2004 / [ed] P. Sas, Heverlee: Katholieke Univ. Leuven , 2004, 965-974 p.Conference paper (Refereed)
    Abstract [en]

    Knowledge of the in-cylinder pressure pulse in IC engines is of main importance in order to fulfill the requirements on low fuel consumption, exhaust emissions and noise. Direct measurements of the in-cylinder pressure are not suitable outside the laboratory environment due to a number of drawbacks. In this paper a combined indirect method for the measurement of the cylinder pressure pulse is developed and verified. The method is based on linear transfer functions between cylinder pressure and engine vibration and crankshaft speed, respectively. The combined method shows better results than achieved by either method separately. The low frequency part of the pressure pulse is reconstructed from crankshaft speed measurements while the high frequency part is reconstructed from vibration measurements. However, there is still a frequency region between the methods where neither method gives a reliable prediction.

  • 13.
    Johnsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Localisation of the TDC-position from crankshaft speed fluctuation measurements2002In: Proceedings of the Sixth International Conference on Rotor Dynamics, IFT o MM / [ed] E.J. Hahn; R.B. Randall, Sydney: International Federation for the Theory of Machines and Mechanisms , 2002, 265-272 p.Conference paper (Refereed)
  • 14. Johnsson, Roger
    et al.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Prediction of points and tendencies of the pressure waveform from crankshaft speed measurements2000In: Proceedings of ISMA 25, 2000 International Conference on Noise and Vibration Engineering: 2000 September 13 - 15, [Leuven / [ed] P. Sas, Leuven: Katholieke universiteit , 2000, 907-12 p.Conference paper (Refereed)
    Abstract [en]

    Direct measurements of the pressure inside the engine have a number of limitations that makes the method expensive and only good for laboratory measurements. Therefore an indirect method to measure the pressure is of main interest. In this study a method based on the crankshaft angular speed fluctuation using neural network has been developed. Two points on the pressure pulse have been reconstructed maximum pressure (Pmax) and start of combustion (SOC). Pmax is predicted with an accuracy of 7.7 MPa and SOC with an accuracy of 1.3 degrees.

  • 15.
    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, 1554-1563 p.Article 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.

  • 16.
    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, 413-422 p.Article 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.

  • 17.
    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, 203-213 p.Conference 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.

  • 18.
    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, 17-23 p.Article 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.

  • 19.
    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, 1-7 p., 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.

  • 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 tyre noise based on operational data2012In: Proceedings ISMA 2012: International Conference on Noise and Vibration Engineering, Leuven: Katholieke Universitat , 2012, Vol. 2, 1583-1594 p.Conference 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.

  • 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.
    An auralization model for structure-borne tire noise2015In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 96, 61-67 p.Article 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.

  • 22.
    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, 108-115 p.Article 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.

  • 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.
    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, 283-292 p.Article 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.

  • 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.
    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, 4694-4702 p.Conference 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.

  • 25.
    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, 346-353 p., 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.

  • 26.
    Mishra, Madhav
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Rantatalo, Matti
    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.
    Larsson, Jan-Olof
    SKF Sweden.
    Bellander, Magnus
    SKF Sweden.
    Niemi, Ingemar
    Billerud Karlsborg AB.
    Simulations and Measurements of the Dynamic Response of a Paper Machine Roller2015Conference paper (Refereed)
    Abstract [en]

    The paper industry is a highly automated industry that includes many different production steps where a variety of machine components are used. In the paper machine where the pulp is being transformed into paper, rotating components like bearing mounted rollers play an important part to drive the wire with the pulp through the process. In this type of industry with a serial layout, the failure of a single roller or bearing could lead to stoppage of several production steps with costly consequences as a result. To ensure and optimize the asset availability, a condition based maintenance (CBM) strategy could be implemented. However, CBM is dependent on an appropriate condition monitoring (CM) technique to detect physical phenomenon that defines the state of critical components or systems. For the development of CM techniques, it is therefore important to understand and model the physical behaviour of the system in question. In this paper the behaviour of a roller in a paper machine is analysed using finite element method (FEM). The physical model was compared with vibration measurements collected from an online monitoring system and an experimental modal analysis.

  • 27.
    Mishra, Madhav
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Rantatalo, Matti
    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.
    Larsson, Jan-Olof
    SKF Sweden.
    Bellander, Magnus
    SKF Sweden.
    Niemi, Ingemar
    Billerud Karlsborg AB.
    Simulations and measurements of the dynamic response of a paper machine roller2016In: Insight (Northampton), ISSN 1354-2575, E-ISSN 1754-4904, Vol. 58, no 4, 210-212 p.Article in journal (Refereed)
    Abstract [en]

    The paper industry is a highly automated industry that includes many different production steps, in which a variety of machine components are used. In a paper machine, where the pulp is being transformed into paper, rotating components such as bearing-mounted rollers play an important part in driving the wire with the pulp through the process. In this type of industry with a serial layout, the failure of a single roller or bearing could lead to the stoppage of several production steps, with costly consequences as a result. To ensure and optimise asset availability, a condition-based maintenance (CBM) strategy could be implemented. However, CBM is dependent on an appropriate condition monitoring (CM) technique to detect a physical phenomenon that defines the state of critical components or systems. For the development of CM techniques, it is therefore important to understand and model the physical behaviour of the system in question. In this paper, the behaviour of a roller in a paper machine is analysed using the finite element method (FEM). The physical model was compared with vibration measurements collected from an online monitoring system and an experimental modal analysis.

  • 28.
    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, 695-702 p.Conference 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

  • 29.
    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, 4687-4693 p.Conference 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.

  • 30.
    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, 1343-1353 p.Article 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.

  • 31.
    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, 115-123 p.Article 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.

  • 32.
    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, 982-988 p.Article 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.

  • 33.
    Tingvall, Bror
    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.
    Larsson, Tony
    Vibrationer i gruvindustrin2005Report (Other academic)
    Abstract [sv]

    Exponering för vibrationer anses kunna leda till olika typer av skador på människokroppen. Med de metoder som nyttjas vid losstagning av berg används gruvutrustning som under vissa förutsättningar genererar vibrationer av icke acceptabla nivåer. För att klara de nya kraven på maximala vibrationsnivåer har en satsning gjorts för att kartlägga vibrationsnivåerna i gruvmaskinerna. Kartläggningen av vibrationsnivåer inom svensk gruvindustri syftar till att skapa förståelse för sambandet mellan operatör och utrustning. Resultaten från studierna skall ge kunskap som kan användas för insatser som syftar till att minska vibrationerna samt för information till och utbildning av personalen. Studierna skall också ge underlag som senare kan användas som ett bidrag i arbetet med att reducera vibrationer i gruvmaskiner genom utveckling och förbättringar av stolar, hytter, körcykler, körsätt och enklare mätsystem för vibrationsregistrering (mätlogger). Kartläggningen skall också ge underlag på aktuella vibrationsnivåer och tillåtna exponeringstider i olika gruvmaskiner i enlighet med den nya föreskriften AFS 2005:15

  • 34.
    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, 60-67 p.Conference 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.

  • 35.
    Ågren, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    NVH caused by ABS and ESP in cold climates2009Report (Other academic)
  • 36.
    Ågren, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Zurita-Villarroel, G.
    Luleå tekniska universitet.
    Johnsson, Roger
    Inverse transfer function method to estimate the combustion1998In: Proceedings Inter-noise 98: Sound and silence: setting the balance / [ed] V.C. Goodwin, Auckland: Ministry of Transport , 1998, 433-436 p.Conference paper (Refereed)
1 - 36 of 36
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