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Publications (10 of 83) Show all publications
Johansson, Ö., Pamidi, T. R., Shankar, V. & Löfqvist, T. (2019). Acoustic design principles for energy efficient excitation of a high intensity cavitation zone. In: Martin Ochmann (Ed.), Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September. Paper presented at 23rd International Congress on Acoustics (pp. 948-955). Aachen, Germany
Open this publication in new window or tab >>Acoustic design principles for energy efficient excitation of a high intensity cavitation zone
2019 (English)In: Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September / [ed] Martin Ochmann, Aachen, Germany, 2019, p. 948-955Conference paper, Published paper (Other academic)
Abstract [en]

Energy-efficient process intensification is a key aspect for a sustainable industrial production. To improve energy conversion efficiency high intensity cavitation is a promising method, especially in cases where the material to be treated is valuable and on the micro meter scale. Transient collapsing cavitation bubbles gives powerful effects on objects immersed in fluids, like cellulose fibers, mineral particles, enzymes, etc. The cavitation process needs optimization and control, since optimal conditions is multivariate challenge. This study focuses on different design principles to achieve high intensity cavitation in a specific volume in a continuous flow. This study explores some potential design principles to obtain energy efficient process intensification. The objective is to tune several different resonance phenomena to create a powerful excitation of a flowing suspension (two-phase flow and cavitation bubbles). The reactor is excited by sonotrodes, connected to two coupled resonant tube structures, at the critical frequency. Finally cavitation bubbles are initiated by a flow through a venturi nozzle. The acoustically optimised reactor geometry is modelled in Comsol Multiphysics®, and excited by dedicated ultrasound signals at three different frequencies. The effect of the high intensity cavitation is experimentally evaluated by calorimetric method, foil tests and degree of fibrillation on cellulose fibers.

Place, publisher, year, edition, pages
Aachen, Germany: , 2019
Keywords
Structural acoustics, Ultrasound, Hydrodynamics, Cavitation
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-76063 (URN)978-3-939296-15-7 (ISBN)
Conference
23rd International Congress on Acoustics
Funder
Swedish Energy Agency
Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-09-19
Pamidi, T. R., Johansson, Ö. & Löfqvist, T. (2019). Comparison of Cavitation Effect in Case of Fixed and Free Fibers in an Ultrasound Beaker. In: Martin Ochmann (Ed.), Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September. Paper presented at 23rd International Congress on Acoustics (pp. 8217-8224). Aachen, Germany
Open this publication in new window or tab >>Comparison of Cavitation Effect in Case of Fixed and Free Fibers in an Ultrasound Beaker
2019 (English)In: Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September / [ed] Martin Ochmann, Aachen, Germany, 2019, p. 8217-8224Conference paper, Published paper (Other academic)
Abstract [en]

In this study, we investigate the impact of high-intensity ultrasound treatment on the mechanical properties of pulp fibers. The pulp fiber samples are sonicated in an acoustically optimised beaker where high-intensity ultrasound is generated using a tuned sonotrode device. The idea is to create a controlled resonance to efficiently enhance the sound pressure in the beaker. Input power is 90Watt. The objective is to define the difference between freely suspended fibers in a beaker compared to keeping fibers in a fixed position. The hypothesis is that fiber treatment at a specific input power will be more efficient in the case when fibers are kept in a high pressure zone. Since the fiber wall is a layered structure, it is likely to delaminate internally which will affect the mechanical properties of the fiber. The effect on fiber properties is verified by measuring the ultrasound attenuation spectra for the treated fibers. The attenuation measurements are based on measurements of a low-intensity ultrasound pulse-echo technique. On a macroscopic scale, changes in the attenuation spectra relates to a change in mechanical properties of the fiber wall, since the suspended fibers more or less retain their diameter and length distributions.

Place, publisher, year, edition, pages
Aachen, Germany: , 2019
Keywords
Ultrasonics, Cavitation, Paper pulp, Cellulose fibers
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-76050 (URN)978-3-939296-15-7 (ISBN)
Conference
23rd International Congress on Acoustics
Funder
Swedish Energy Agency
Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-09-18
Pamidi, T. R., Johansson, Ö. & Löfqvist, T. (2018). Comparison of Different Concepts of UltrasoundReactors Using Numerical Simulations. In: : . Paper presented at 16th Meeting of the European Society of Sonochemistry.
Open this publication in new window or tab >>Comparison of Different Concepts of UltrasoundReactors Using Numerical Simulations
2018 (English)Conference paper, Poster (with or without abstract) (Other (popular science, discussion, etc.))
Abstract [en]

Sonochemical reactors are used for process intensification based on efficientenergy transfer due to ultrasound in order to cause transient cavitation in the medium.Ultrasonic reactors are extensively used for numerous applications due to their differentfeatures. The process of ultrasound cavitation can be defined as generation, growth andviolent collapse of microbubbles under ultrasonic irradiation which can release a highamount of energy in a small volume. The released energy causes a sudden increase intemperature and pressure which thereby can lead to extensive process intensification. Thepresent work deals with the evaluation of two different configurations of ultrasound reactorsusing both numerical modeling and experimental verification. The evaluation is based onprediction of the pressure distribution, verified by foil tests and with calorimetric method.The two reactors were developed to be used for the treatment of cellulose fibers to improveenergy efficiency in the fibrillation process. The goal is to optimize cavitation intensityand minimize the coupling loss factors. The development and evaluation of these two reactorconcepts aim to improve the design methodology for a scalable flow through reactor conceptwith high yield and energy efficiency

National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-73782 (URN)
Conference
16th Meeting of the European Society of Sonochemistry
Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-09-06
Johansson, Ö., Pamidi, T. R. & Löfqvist, T. (2017). Design of a high-intensity ultrasound reactor. In: : . Paper presented at 2017 IEEE International Ultrasonics Symposium (IUS),Washington, DC, 6-9 Sept. 2017. Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Design of a high-intensity ultrasound reactor
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Design, and optimization of ultrasonic reactors are important objectives in sonochemical processing. The recent expansion of the use of ultrasonic reactors in various research areas all faces the problem of scaling up from laboratory results to industrial purposes. A traditional ultrasonic reactor usually has several issues, such as low effectiveness as well as complex and unstable system performance, which all are unfavorable for efficient sonochemical processing. This study addresses these issues and investigates a new flow type ultrasonic reactor designed to generate transient cavitation as the main source for ultrasound. Some important factors like pressure, material, flow and geometry are considered in the design. Numerical optimization as well as experimental investigations are performed to reach an optimized, energy-efficient and controlled ultrasound cavitation reactor. Results from numerical modeling are used for acoustic optimization of the reactor, which is driven with three transducers mounted radially in the reactor wall with 120° spacing. The final reactor is excited with dual frequencies a total of 9 sonotrodes. The reactor is intended to be used in studies of pre-treatment of cellulose fibers aiming at developing an alternative, energy efficient fibrillation process and for ultrasound leaching of minerals.

Place, publisher, year, edition, pages
Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017
National Category
Fluid Mechanics and Acoustics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Acoustics; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-66534 (URN)10.1109/ULTSYM.2017.8092948 (DOI)978-1-5386-3383-0 (ISBN)
Conference
2017 IEEE International Ultrasonics Symposium (IUS),Washington, DC, 6-9 Sept. 2017
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-24Bibliographically approved
Johansson, Ö., Pamidi, T. R. & Löfqvist, T. (2017). Design of a high-intensity ultrasound reactor. In: IEEE International Ultrasonics Symposium, IUS: . Paper presented at 2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017. Piscataway, NJ: IEEE Computer Society, Article ID 8091660.
Open this publication in new window or tab >>Design of a high-intensity ultrasound reactor
2017 (English)In: IEEE International Ultrasonics Symposium, IUS, Piscataway, NJ: IEEE Computer Society, 2017, article id 8091660Conference paper, Published paper (Refereed)
Abstract [en]

Design, and optimization of ultrasonic reactors are important objectives in sonochemical processing. The recent expansion of the use of ultrasonic reactors in various research areas all faces the problem of scaling up from laboratory results to industrial purposes. A traditional ultrasonic reactor usually has several issues, such as low effectiveness as well as complex and unstable system performance, which all are unfavorable for efficient sonochemical processing. This study addresses these issues and investigates a new flow type ultrasonic reactor designed to generate transient cavitation as the main source for ultrasound. Some important factors like pressure, material, flow and geometry are considered in the design. Numerical optimization as well as experimental investigations are performed to reach an optimized, energy-efficient and controlled ultrasound cavitation reactor. Results from numerical modeling are used for acoustic optimization of the reactor, which is driven with three transducers mounted radially in the reactor wall with 120° spacing. The final reactor is excited with dual frequencies a total of 9 sonotrodes. The reactor is intended to be used in studies of pre-treatment of cellulose fibers aiming at developing an alternative, energy efficient fibrillation process and for ultrasound leaching of minerals

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Computer Society, 2017
Series
IEEE International Ultrasonics Symposium, E-ISSN 1948-5719
National Category
Fluid Mechanics and Acoustics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Acoustics; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-66533 (URN)10.1109/ULTSYM.2017.8091660 (DOI)000416948400055 ()2-s2.0-85039413569 (Scopus ID)978-1-5386-3383-0 (ISBN)
Conference
2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2018-01-16Bibliographically approved
Johansson, Ö., Löfqvist, T. & Pamidi, T. R. (2017). Design of high-intensity ultrasound reactor. In: IEEE International Ultrasonics Symposium, IUS: . Paper presented at 2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017. Piscataway, NJ: IEEE Computer Society, Article ID 8092948.
Open this publication in new window or tab >>Design of high-intensity ultrasound reactor
2017 (English)In: IEEE International Ultrasonics Symposium, IUS, Piscataway, NJ: IEEE Computer Society, 2017, article id 8092948Conference paper, Published paper (Refereed)
Abstract [en]

Design and optmiziation of ultrasonic reactors are important objectives in sonochemical processing. The recent expansion of the use of ultrasonic reactors in various research projects all faces the problem of scaling up laboratory results for industrial use. A traditional ultrasonic reactor usually has several issues, such as low effectiveness and complex and unstable system performance, which all are unfavorable for efficient sonochemical processing. This study adresses these issues and investigates a new flow type ultrasonic reactor designed to generate transient cavitation as the main source for ultrasound for sonochemical processing. This study proposes the principle of the flow type ultrasonic reactor design to generate transient cavitation. The objective of this work is to design an ultrasonic reactor with a new geometry. The idea is to improve process efficiency based on resonance enhanced ultrasound controlled cavitation

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Computer Society, 2017
Series
IEEE International Ultrasonics Symposium, ISSN 1948-5719
National Category
Fluid Mechanics and Acoustics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Acoustics; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-67244 (URN)10.1109/ULTSYM.2017.8092948 (DOI)000416948403005 ()2-s2.0-85039437533 (Scopus ID)978-1-5386-3383-0 (ISBN)
Conference
2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017
Available from: 2018-01-11 Created: 2018-01-11 Last updated: 2018-01-16Bibliographically approved
Johansson, Ö., Pamidi, T., Khoshkhoo, M. & Sandström, Å. (2017). Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation
2017 (English)Report (Other academic)
Abstract [en]

The project aims to use ultrasound controlled cavitation to achieve a more energy efficient leaching process. Locally, collapsing cavitation bubbles cause an extremely high pressure, shock waves and high temperature, which provide an opportunity to perform the leaching process at a much lower temperature than in an autoclave (20 bar overpressure and 220 ° C). The results show that the method works, but that a higher static pressure and thus temperatures are necessary to achieve a leaching recovery rate corresponding to today's autoclave technology. Another process parameter of importance is flow control and the initiation of cavitation bubbles that occur through a geometrically optimized nozzle (orifice plate). Numerical and experimental adaptation of the developed reactor with respect to the leaching conditions (Sodium hydroxide and Scheelite concentrate), required more time than expected. Best test results show that an energy supplement with ultrasonic controlled cavitation of 104 kWh / kg increases the leaching recovery by 21%. The leaching reagent temperature 60° C was determined regarding available reference data and was thought to be close to optimum for intensive cavitation in atmospheric pressure. Optimum temperature relates to the leaching reagent, vaporization temperature, density, boiling point, surface tension, and viscosity. Generally, for leaching is that higher temperatures are required to increase the chemical reaction rate (requires overpressure). The modified reactor principle provides stable results and is possible to scale up. Higher cavitation intensity for shorter finishing time and higher recovery rate require advanced flow induction, multiple excitation frequencies adapted to the optimized reactor geometry, as well as optimal process pressure and temperature.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017. p. 20
Series
Research report / Luleå University of Technology, ISSN 1402-1528
Keywords
Ultrasound, Cavitation, Leaching, Scheelite, Vibro acoustic optimization
National Category
Mineral and Mine Engineering Fluid Mechanics and Acoustics Metallurgy and Metallic Materials
Research subject
Engineering Acoustics; Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-66286 (URN)978-91-7790-160-0 (ISBN)
Projects
Vinnova SIP-Strim
Funder
Vinnova, 2016-02620Vinnova
Available from: 2017-10-27 Created: 2017-10-27 Last updated: 2019-09-11Bibliographically approved
Wijaya, A. R. & Johansson, Ö. (2016). Difference thresholds of multi-axis whole-body vibration. In: IEEE International Conference on Industrial Engineering and Engineering Management: . Paper presented at 2016 International Conference on Industrial Engineering and Engineering Management, IEEM 2016, Bali, Indonesia,4-7 December 2016 (pp. 1760-1764). Piscataway, NJ: IEEE Computer Society, Article ID 7798180.
Open this publication in new window or tab >>Difference thresholds of multi-axis whole-body vibration
2016 (English)In: IEEE International Conference on Industrial Engineering and Engineering Management, Piscataway, NJ: IEEE Computer Society, 2016, p. 1760-1764, article id 7798180Conference paper, Published paper (Refereed)
Abstract [en]

A laboratory study was conducted to investigate the effects of lateral and horizontal vibration on the difference threshold of vertical vibration. Twelve male subjects sat on a rigid seat and were exposed to four different vibration conditions (pure vertical vibration; combination of horizontal and vertical vibration; combination of lateral and vertical vibration; combination of horizontal, lateral and vertical vibration). Vertical vibration for four conditions was 5 Hz sinusoidal with a magnitude of 1 ms-2 r.m.s. Horizontal and lateral vibration for the last three conditions were sinusoidal with magnitude 0.5 ms-2 r.m.s. and contained ten frequencies (1 to 8 Hz in third-octave band step). The frequency-weighted acceleration of the ten frequencies was equal. Results showed that horizontal and lateral vibrations have different effects on the difference threshold of vertical vibration. The combination of vertical and horizontal vibration gave a significantly lower difference threshold of vertical vibration than the combination of vertical and lateral vibration

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Computer Society, 2016
Series
IEEE International Conference on Industrial Engineering and Engineering Management, ISSN 2157-3611
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-61851 (URN)10.1109/IEEM.2016.7798180 (DOI)000392208100357 ()2-s2.0-85009874493 (Scopus ID)9781509036653 (ISBN)
Conference
2016 International Conference on Industrial Engineering and Engineering Management, IEEM 2016, Bali, Indonesia,4-7 December 2016
Available from: 2017-02-07 Created: 2017-02-07 Last updated: 2017-11-24Bibliographically approved
Johansson, Ö. (2016). Energieffektivisering genom flödesexciterad, resonansförstärkt och ultraljudskontrollerad kavitation: Delprojekt inom Mekmassainitiativet för energieffektivitet (E2MPi) (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Energieffektivisering genom flödesexciterad, resonansförstärkt och ultraljudskontrollerad kavitation: Delprojekt inom Mekmassainitiativet för energieffektivitet (E2MPi)
2016 (Swedish)Report (Other academic)
Abstract [sv]

Projektet syftar till att öka kunskap och förståelse för hur kavitation kan användas och kontrolleras för att koncentrera bearbetningsenergin till frekvensområden som ger effektiv påverkan av cellulosafibrer. Tanken är att skapa ett komplement eller en alternativ teknik till dagens raffinörer. Idén bygger på att resonansförstärkt ultraljud initierar och kollapsar kavitationsbubblor på ytan av cellulosafibrer i vatten. Tidigare forskning har visat att ultraljudsbehandling ger önskade effekter på fiberväggen. Energieffektiviteten har dock inte varit tillräckligt bra och uppskalning är en identifierad problematik. Den föreslagna metoden syftar till att via numerisk och experimentell optimering åstadkomma en energieffektiv och kontrollerad bearbetning av fiberväggen. Den långsiktiga målsättningen är att halvera energiförbrukningen i jämförelse med dagens raffinörer.Hypotesen är att ultraljudskontrollerad kavitation fungerar beroende på att transient asymmetrisk kollapsa av kavitationsbubblor kan ge upphov till extrema tryck på en liten yta. Principen bygger på små att gasbubblor i vatten exciteras av högintensivt ultraljud. Vid en viss kritisk storlek kommer bubblan i resonans och då växer den snabbt. Yttre trycket når sitt max i samband med att bubblan kollapsar. Ultraljud med konstant frekvens (ex 20 kHz) gör att mängder av bubblor, med varierande storlek och harmoniskt relaterade resonansfrekvenser, kollapsar. De jetstrålar i mikroskala som uppstår vid asymmetrisk kollaps av kavitationsbubblor antas ge en mekanisk påverkan av cellulosafibrer i form av både inre och yttre fibrillering.Projektet har resulterat i en utveckling och verifiering av en FE-baserad optimeringsstrategi för flödesinducerad och ultraljudskontrollerad kavitation. Den framtagna kavitationsreaktorn består av en dysa och ett vattenfyllt reaktorrör exciterat med ultraljud. Fibersuspensionen strömmar genom ett inre tunnväggigt rör i reaktorns centrum. Beräkningsmodellen ger stabila resultat avseende ultraljudsexcitering och är kalibrerad med experimentellt bestämda förlustfaktorer för aktuell prototypreaktor. Simuleringar av flödesinducerad kavitation begränsades till ren vattenfas. Den framtagna geometrin är dock verifierad avseende strömning med fibersuspension. Experimentella resultat utan flöde visar mycket god överenstämmelse avseende beräknade svängningsformer och resonansfrekvenser. Beräknad ljudtrycksnivå är högre än uppmätt beroende på de olinjäriteter som uppstår när vätskan utsätts för mycket höga amplituder. Dessutom är förlustfaktorn något högre i experimenten och trycksignalens verkliga effektinnehåll ligger delvis utanför mätområdet.Beräkningsjämförelser med ett alternativt och kommersiellt förekommande reaktorkoncept (behållare), visar att den nyutvecklade rörreaktorn ger högre intensitet i den optimala zonen (+120%). Den totala förlustfaktorn för rörreaktorn är ca 1.1 % vid resonans. Tillförd elektrisk effekt bestäms genom att mäta ström och spänning när kavitationsreaktorn exciteras vid sin resonansfrekvens. Optimal kavitationseffekt identifieras av ljudtrycksamplitudkvoten: pUS(f1.5)/pUS(f1). Kavitation ger effektiv bearbetning av fibermaterialet i zonen för maximal tryckvariation. Initiering av flödesinducerad kavitation med justerbar Venturi-dysa ger intensivare kavitation samt god blandning och sammanhållen fibersuspension. Test och verifiering med fibermaterial är baserad på en HT-CTMP fiber (torkad/aldrig torkad) med 0.5%, 1% och 2% konc. Positiv förändring av fiberkvalitet uppstod endast i några av testfallen. I test med både flödesinducerad och ultraljudsstyrd kavitation uppstod bäst resultat vid lägst energinivå (470 kWh/adt). I övriga testfall finns misstanke om att fibermaterialet har förstörts av för hög kavitationsintensitet. En slutsats som delvis verifieras av SEM-analys av behandlat fibermaterial. Tillförd energinivå var dock inte tillräcklig för att uppnå godkänd massakvalitet, dvs. lika bra eller bättre dragindex. I nuläget går det inte att fastställa om föreslagen metod är energieffektiv på grund av svårigheten i att jämföra en prototyp och fullskaleanläggning. En uppenbar förbättringsmöjlighet med framtagen reaktorlösningen är att förlänga reaktorröret (ej realiserbart i prototypskedet). Den valda reaktorlösningen kan skalas upp genom parallellkoppling och seriekoppling. Seriekoppling och längre reaktorrör kräver ett högre matningstryck vilket kan ge en fördel med högre kavitationsintensitet. Den experimentella valideringen är begränsad till en excitationsfrekvens (22.7 kHz) och normaltryck. En kombination med högre ultraljudsfrekvenser (37 och/eller 53 kHz för rörreaktorn) är en möjlig förbättring genom att de aktiva bubblornas storlek reduceras och får en storleksordning som är bättre anpassad till fiberväggens storlek och struktur. En annan förbättringsaspekt är ett högre statiskt tryck, vilket ökar kavitationsintensiteten och möjliggör en förkortad exponeringstid.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2016. p. 49
Series
Research report / Luleå University of Technology, ISSN 1402-1528
Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Engineering mechanics - Other engineering mechanics, Ultrasound structural acoustics resonance cavitation hydro dynamic, Acoustics, optimizatin, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära, Teknisk mekanik - Övrig teknisk mekanik
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-23714 (URN)81e643ab-e6f8-482b-9bee-8470bdd309ba (Local ID)978-91-7583-645-4 (ISBN)81e643ab-e6f8-482b-9bee-8470bdd309ba (Archive number)81e643ab-e6f8-482b-9bee-8470bdd309ba (OAI)
Note
Godkänd; 2016; 20160608 (orjo)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Nykänen, A., Johnsson, R., Sirkka, A. & Johansson, Ö. (2013). Assessment of changes in preference ratings of auralized engine sounds caused by changes in frequency resolution of transfer functions (ed.). Paper presented at . Applied Acoustics, 74(12), 1343-1353
Open this publication in new window or tab >>Assessment of changes in preference ratings of auralized engine sounds caused by changes in frequency resolution of transfer functions
2013 (English)In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 74, no 12, p. 1343-1353Article in journal (Refereed) Published
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.

National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-9325 (URN)10.1016/j.apacoust.2013.05.005 (DOI)000324227100005 ()2-s2.0-84879340090 (Scopus ID)7ecb64fe-34ba-46dd-82f7-60bfe2d531b4 (Local ID)7ecb64fe-34ba-46dd-82f7-60bfe2d531b4 (Archive number)7ecb64fe-34ba-46dd-82f7-60bfe2d531b4 (OAI)
Note
Validerad; 2013; 20130626 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2955-2776

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