Gerrit Vermeir - Academia.edu (original) (raw)

Papers by Gerrit Vermeir

Research paper thumbnail of Binaural sound source localization in real and virtual rooms

Research paper thumbnail of The use of U50 to calculate the optimal absorption in a classroom

Journal of The Acoustical Society of America, 2008

ABSTRACT Common measures for the speech intelligibility predict increasing values with increasing... more ABSTRACT Common measures for the speech intelligibility predict increasing values with increasing absorption in empty classrooms. Measurements confirm this relation, so it seems as if an anechoic room is the best place to teach. However, there are two problems: the sound pressure level at the back row is too low when compared to the levels on the front row or when compared to the noise level caused by pupils plus ventilation systems. A simple method is proposed based on U50, which gives the relation between the sound energy from direct sound (from a teacher or a pupil) plus early reflections on one side and late reflections plus noise on the other. Barron's formula for the sound level decrease in a concert hall is included to predict the sound level drop through the classroom. Model results indicate that the absorption coefficient should be in the order of 20 to 30% if the signal to noise ratio is in the range between +5 to -5 dB. These values seem low, but measurements in existing classrooms show low signal to noise levels as well.

Research paper thumbnail of Perceptual validation of virtual room acoustics: Sound localisation and speech understanding

Applied Acoustics, 2011

The reliability of algorithms for room acoustic simulations has often been confirmed on the basis... more The reliability of algorithms for room acoustic simulations has often been confirmed on the basis of the verification of predicted room acoustical parameters. This paper presents a complementary perceptual validation procedure consisting of two experiments, respectively dealing with speech intelligibility, and with sound source front–back localisation.The evaluated simulation algorithm, implemented in software ODEON®, is a hybrid method that is based on an image source algorithm for the prediction of early sound reflection and on ray-tracing for the later part, using a stochastic scattering process with secondary sources. The binaural room impulse response (BRIR) is calculated from a simulated room impulse response where information about the arriving time, intensity and spatial direction of each sound reflection is collected and convolved with a measured Head Related Transfer Function (HRTF). The listening stimuli for the speech intelligibility and localisation tests are auralised convolutions of anechoic sound samples with measured and simulated BRIRs.Perception tests were performed with human subjects in two acoustical environments, i.e. an anechoic and reverberant room, by presenting the stimuli to subjects in a natural way, and via headphones by using two non-individualized HRTFs (artificial head and hearing aids placed on the ears of the artificial head) of both a simulated and a real room.Very good correspondence is found between the results obtained with simulated and measured BRIRs, both for speech intelligibility in the presence of noise and for sound source localisation tests. In the anechoic room an increase in speech intelligibility is observed when noise and signal are presented from sources located at different angles. This improvement is not so evident in the reverberant room, with the sound sources at 1-m distance from the listener. Interestingly, the performance of people for front–back localisation is better in the reverberant room than in the anechoic room.The correlation between people’s ability for sound source localisation on one hand, and their ability for recognition of binaurally received speech in reverberation on the other hand, is found to be weak.

Research paper thumbnail of Designing spaces for every listener

Universal Access in The Information Society, 2010

Inclusive design aims at objects and environments that are accessible, usable and comfortable for... more Inclusive design aims at objects and environments that are accessible, usable and comfortable for all people throughout their entire lifespan. In architecture, this aim is usually associated with physical accessibility. Yet acoustic qualities may considerably impact usability and comfort as well, especially in spaces for listening. This case study explores the notion of acoustic comfort for all in the context of university education. One auditorium, situated in a historic building and subject to renovation in the near future, is studied in detail: acoustic obstacles are identified in collaboration with user/experts and are measured in situ; specific interventions are proposed in consultation with building professionals, technicians and conservation specialists and are tested using dedicated acoustic simulation software. The study draws attention to the importance of acoustic comfort for all and offers a first view of which solutions are possible and desirable and how these can be obtained.

Research paper thumbnail of Architecture for every listener

Research paper thumbnail of Localization of the Speaker in a Real and Virtual Reverberant Room

Research paper thumbnail of The use of virtual acoustics in the evaluation and development of binaural hearing aid algorithms

Journal of The Acoustical Society of America, 2008

Research paper thumbnail of The application of the soundscape approach in the evaluation of the urban public spaces

Journal of The Acoustical Society of America, 2008

Research paper thumbnail of Methods for the characterization of sound packages containing visco-elastic and anisotropic porous materials

Research paper thumbnail of A wave based model to describe the niche effect in sound transmission loss determination of single and double walls

Research paper thumbnail of Localizing The Teacher In The Virtual Classroom

Research paper thumbnail of The use of virtual acoustics in the evaluation and development of binaural hearing aid algorithms

The Journal of the Acoustical Society of America, 2008

Research paper thumbnail of Binaural sound source localization in real and virtual rooms

Research paper thumbnail of Perceptual validation of virtual room acoustics: Sound localisation and speech understanding

Applied Acoustics, 2011

... Monika Rychtáriková a , b , Corresponding Author Contact Information , E-mail The Correspondi... more ... Monika Rychtáriková a , b , Corresponding Author Contact Information , E-mail The Corresponding Author , Tim van den Bogaert c , Gerrit Vermeir d and ... and the other one based on sound recorded by hearing aids measured when placed on ears of the artificial head (HAM). ...

Research paper thumbnail of Application of the Wave Based Prediction Technique for the Analysis of the Coupled Vibro-Acoustic Behaviour of a 3D Cavity

Proceedings of the …, 2002

In the automotive industry, vehicle interior acoustics has become an important design criterion. ... more In the automotive industry, vehicle interior acoustics has become an important design criterion. Both legal restrictions and the growing demand for comfort, force the car manufacturers to optimize the vibro-acoustic behaviour of their products. The tendency to minimise the ...

Research paper thumbnail of A Wave Based Model to Predict the Niche Effect on Sound Transmission Loss of Single and Double Walls

Acta Acustica united with Acustica, 2012

Research paper thumbnail of Soundscape categorization on the basis of objective acoustical parameters

Applied Acoustics

A soundscape assessment method that is suitable for the automatic categorization of binaurally re... more A soundscape assessment method that is suitable for the automatic categorization of binaurally recorded sound in urban public places is presented. Soundscape categories are established as a result of an automatic clustering algorithm based on multi-parameter analysis by 13 acoustical parameters used as similarity measures, on a large set of sound recordings. One of the main advantages of the followed approach allows to take into account an optimized set of parameters that are judged relevant and necessary for an appropriate description of the sampled acoustical scenarios. The Euclidian distance based clustering of the 370 recordings of typical situations based on these parameters, allows to categorize each binaurally recorded sound sample into one of 20 proposed clusters (soundscape categories). The common features among members within each cluster allow to identify “how the acoustical scenario of the members sounds like”. The hybrid use of an optimized set of standard acoustical quantities, such as sound pressure level, together with well known psychoacoustical parameters that directly relate to human perception of sound, makes the propose method very robust.

Research paper thumbnail of Binaural sound source localization in real and virtual rooms

Research paper thumbnail of The use of U50 to calculate the optimal absorption in a classroom

Journal of The Acoustical Society of America, 2008

ABSTRACT Common measures for the speech intelligibility predict increasing values with increasing... more ABSTRACT Common measures for the speech intelligibility predict increasing values with increasing absorption in empty classrooms. Measurements confirm this relation, so it seems as if an anechoic room is the best place to teach. However, there are two problems: the sound pressure level at the back row is too low when compared to the levels on the front row or when compared to the noise level caused by pupils plus ventilation systems. A simple method is proposed based on U50, which gives the relation between the sound energy from direct sound (from a teacher or a pupil) plus early reflections on one side and late reflections plus noise on the other. Barron's formula for the sound level decrease in a concert hall is included to predict the sound level drop through the classroom. Model results indicate that the absorption coefficient should be in the order of 20 to 30% if the signal to noise ratio is in the range between +5 to -5 dB. These values seem low, but measurements in existing classrooms show low signal to noise levels as well.

Research paper thumbnail of Perceptual validation of virtual room acoustics: Sound localisation and speech understanding

Applied Acoustics, 2011

The reliability of algorithms for room acoustic simulations has often been confirmed on the basis... more The reliability of algorithms for room acoustic simulations has often been confirmed on the basis of the verification of predicted room acoustical parameters. This paper presents a complementary perceptual validation procedure consisting of two experiments, respectively dealing with speech intelligibility, and with sound source front–back localisation.The evaluated simulation algorithm, implemented in software ODEON®, is a hybrid method that is based on an image source algorithm for the prediction of early sound reflection and on ray-tracing for the later part, using a stochastic scattering process with secondary sources. The binaural room impulse response (BRIR) is calculated from a simulated room impulse response where information about the arriving time, intensity and spatial direction of each sound reflection is collected and convolved with a measured Head Related Transfer Function (HRTF). The listening stimuli for the speech intelligibility and localisation tests are auralised convolutions of anechoic sound samples with measured and simulated BRIRs.Perception tests were performed with human subjects in two acoustical environments, i.e. an anechoic and reverberant room, by presenting the stimuli to subjects in a natural way, and via headphones by using two non-individualized HRTFs (artificial head and hearing aids placed on the ears of the artificial head) of both a simulated and a real room.Very good correspondence is found between the results obtained with simulated and measured BRIRs, both for speech intelligibility in the presence of noise and for sound source localisation tests. In the anechoic room an increase in speech intelligibility is observed when noise and signal are presented from sources located at different angles. This improvement is not so evident in the reverberant room, with the sound sources at 1-m distance from the listener. Interestingly, the performance of people for front–back localisation is better in the reverberant room than in the anechoic room.The correlation between people’s ability for sound source localisation on one hand, and their ability for recognition of binaurally received speech in reverberation on the other hand, is found to be weak.

Research paper thumbnail of Designing spaces for every listener

Universal Access in The Information Society, 2010

Inclusive design aims at objects and environments that are accessible, usable and comfortable for... more Inclusive design aims at objects and environments that are accessible, usable and comfortable for all people throughout their entire lifespan. In architecture, this aim is usually associated with physical accessibility. Yet acoustic qualities may considerably impact usability and comfort as well, especially in spaces for listening. This case study explores the notion of acoustic comfort for all in the context of university education. One auditorium, situated in a historic building and subject to renovation in the near future, is studied in detail: acoustic obstacles are identified in collaboration with user/experts and are measured in situ; specific interventions are proposed in consultation with building professionals, technicians and conservation specialists and are tested using dedicated acoustic simulation software. The study draws attention to the importance of acoustic comfort for all and offers a first view of which solutions are possible and desirable and how these can be obtained.

Research paper thumbnail of Architecture for every listener

Research paper thumbnail of Localization of the Speaker in a Real and Virtual Reverberant Room

Research paper thumbnail of The use of virtual acoustics in the evaluation and development of binaural hearing aid algorithms

Journal of The Acoustical Society of America, 2008

Research paper thumbnail of The application of the soundscape approach in the evaluation of the urban public spaces

Journal of The Acoustical Society of America, 2008

Research paper thumbnail of Methods for the characterization of sound packages containing visco-elastic and anisotropic porous materials

Research paper thumbnail of A wave based model to describe the niche effect in sound transmission loss determination of single and double walls

Research paper thumbnail of Localizing The Teacher In The Virtual Classroom

Research paper thumbnail of The use of virtual acoustics in the evaluation and development of binaural hearing aid algorithms

The Journal of the Acoustical Society of America, 2008

Research paper thumbnail of Binaural sound source localization in real and virtual rooms

Research paper thumbnail of Perceptual validation of virtual room acoustics: Sound localisation and speech understanding

Applied Acoustics, 2011

... Monika Rychtáriková a , b , Corresponding Author Contact Information , E-mail The Correspondi... more ... Monika Rychtáriková a , b , Corresponding Author Contact Information , E-mail The Corresponding Author , Tim van den Bogaert c , Gerrit Vermeir d and ... and the other one based on sound recorded by hearing aids measured when placed on ears of the artificial head (HAM). ...

Research paper thumbnail of Application of the Wave Based Prediction Technique for the Analysis of the Coupled Vibro-Acoustic Behaviour of a 3D Cavity

Proceedings of the …, 2002

In the automotive industry, vehicle interior acoustics has become an important design criterion. ... more In the automotive industry, vehicle interior acoustics has become an important design criterion. Both legal restrictions and the growing demand for comfort, force the car manufacturers to optimize the vibro-acoustic behaviour of their products. The tendency to minimise the ...

Research paper thumbnail of A Wave Based Model to Predict the Niche Effect on Sound Transmission Loss of Single and Double Walls

Acta Acustica united with Acustica, 2012

Research paper thumbnail of Soundscape categorization on the basis of objective acoustical parameters

Applied Acoustics

A soundscape assessment method that is suitable for the automatic categorization of binaurally re... more A soundscape assessment method that is suitable for the automatic categorization of binaurally recorded sound in urban public places is presented. Soundscape categories are established as a result of an automatic clustering algorithm based on multi-parameter analysis by 13 acoustical parameters used as similarity measures, on a large set of sound recordings. One of the main advantages of the followed approach allows to take into account an optimized set of parameters that are judged relevant and necessary for an appropriate description of the sampled acoustical scenarios. The Euclidian distance based clustering of the 370 recordings of typical situations based on these parameters, allows to categorize each binaurally recorded sound sample into one of 20 proposed clusters (soundscape categories). The common features among members within each cluster allow to identify “how the acoustical scenario of the members sounds like”. The hybrid use of an optimized set of standard acoustical quantities, such as sound pressure level, together with well known psychoacoustical parameters that directly relate to human perception of sound, makes the propose method very robust.