The Journal of the Acoustical Society of America, 2015
The aim of this letter is to address a little understood question in sound source localization: C... more The aim of this letter is to address a little understood question in sound source localization: Can the distance of a near sound source affect our own perception of its elevation? The issue is studied by means of an objective analysis of a database of distance-dependent head-related transfer functions (HRTFs) of a KEMAR (Knowles Electronic Manikin for Acoustic Research) mannequin with different pinnae on a dense spatial grid. Iso-directional HRTFs are compared through spectral error metrics; results indicate significant distance-dependent HRTF modifications due to the pinna occur when the source is close to the interaural axis.
This paper addresses the problem of modeling head-related transfer functions (HRTFs) for 3-D audi... more This paper addresses the problem of modeling head-related transfer functions (HRTFs) for 3-D audio rendering in the front hemisphere. Following a structural approach, we build a model for real-time HRTF synthesis which allows to control separately the evolution of different acoustic phenomena such as head diffraction, ear resonances, and reflections through the design of distinct filter blocks. Parameters to be fed to the model are both derived from mean spectral features in a collection of measured HRTFs and anthropometric features of the specific subject (taken from a photograph of his/her outer ear), hence allowing model customization. Visual analysis of the synthesized HRTFs reveals a convincing correspondence between original and reconstructed spectral features in the chosen spatial range. Furthermore, a possible experimental setup for dynamic psycho acoustical evaluation of such model is depicted.
This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D... more This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D sound rendering. Following a structural approach, we aim at constructing a model for PRTF synthesis which allows to control separately the evolution of ear resonances and spectral notches through the design of two distinct filter blocks. Taking such model as endpoint, we propose a method based on the McAulay-Quatieri partial tracking algorithm to extract the frequencies of the most important spectral notches. Ray-tracing analysis performed on the so obtained tracks reveals a convincing correspondence between extracted frequencies and pinna geometry of a bunch of subjects.
Purpose: The paper presents a system for customized binaural audio delivery based on the extracti... more Purpose: The paper presents a system for customized binaural audio delivery based on the extraction of relevant features from a 2-D representation of the listener’s pinna.
Design/methodology/approach: The most significant pinna contours are extracted by means of multi-flash imaging, and they provide values for the parameters of a structural head-related transfer function (HRTF) model. The HRTF model spatializes a given sound file according to the listener’s
head orientation, tracked by sensor-equipped headphones, with respect to the virtual sound source.
Findings: A preliminary localization test shows that the model is able to statically render the elevation of a virtual sound source better than non-individual HRTFs.
Research limitations/implications:
Results encourage a deeper analysis of the psychoacoustic impact that the individualized HRTF model has on perceived elevation of virtual sound sources.
Practical implications: The model has low complexity and is suitable for implementation on mobile devices. The resulting hardware/software package will hopefully allow an easy and low-tech fruition of custom spatial audio to any user.
Originality/value: We show that custom binaural audio can be successfully deployed without the need of cumbersome subjective measurements.
This paper considers the problem of 3-D sound rendering in the near field through a low-order HRT... more This paper considers the problem of 3-D sound rendering in the near field through a low-order HRTF model. Here we concentrate on diffraction effects caused by the human head which we model as a rigid sphere. For relatively close source distances there already exists an algorithm that gives a good approximation to analytical spherical HRTF curves; yet, due to excessive
Advanced models for 3D audio rendering are increasingly needed in the networked electronic media ... more Advanced models for 3D audio rendering are increasingly needed in the networked electronic media world, and play a central role within the strategic research objectives identified in the NEM research agenda. This paper presents a model for sound spatialization which includes additional features with respect to existing systems, being parametrized according to anthropometric information of the user, and being based
Generalized head-related transfer functions (HRTFs) represent a cheap and straightforward mean of... more Generalized head-related transfer functions (HRTFs) represent a cheap and straightforward mean of providing 3D rendering in headphone reproduction. However, they are known to produce evident sound localization errors, including incorrect perception of elevation, front-back reversals, and lack of externalization, especially when head tracking is not utilized in the reproduction . Therefore, individual anthropometric features have a key role in characterizing HRTFs. On the other hand, HRTF measurements on a significant number of subjects are both expensive and inconvenient. This short paper briefly presents a structural HRTF model that, if properly rendered through a proposed hardware (wireless headphones augmented with motion and vision sensors), can be used for an efficient and immersive sound reproduction. Special care is reserved to the contribution of the external ear to the HRTF: data and results collected to date by the authors allow parametrization of the model according to in...
2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2014
A novel approach to the selection of generic head-related transfer functions (HRTFs) for binaural... more A novel approach to the selection of generic head-related transfer functions (HRTFs) for binaural audio rendering through headphones is formalized and described in this paper. A reflection model applied to the user's ear picture facilitates extraction of the relevant anthropometric cues that are used for selecting two HRTF sets in a database fitting that user, whose localization performances are evaluated in a complete psychoacoustic experiment. The proposed selection increases the average elevation performances of 17% (with a peak of 34%) with respect to generic HRTFs from an anthropomorphic mannequin. It also significantly enhances externalization and reduces the number of up/down reversals.
2013 18th International Conference on Digital Signal Processing (DSP), 2013
A novel approach to the modeling of head-related transfer functions (HRTFs) for binaural audio re... more A novel approach to the modeling of head-related transfer functions (HRTFs) for binaural audio rendering is formalized and described in this paper. Mixed structural modeling (MSM) can be seen as the generalization and extension of the structural modeling approach first defined by Brown and Duda back in 1998. Possible solutions for building partial HRTFs (pHRTFs) of the head, torso, and pinna of a specific listener are first described and then used in the construction of two possible mixed structural models of a KEMAR mannequin. Thanks to the flexibility of the MSM approach, an exponential number of solutions for building custom binaural audio displays can be considered and evaluated, the final aim of the process being the achievement of a HRTF model fully customizable by the listener.
This paper proposes a repository for the organization of full-and partial-body Head-Related Impul... more This paper proposes a repository for the organization of full-and partial-body Head-Related Impulse Responses (HRIRs/pHRIRs) and Headphone Impulse Responses (HpIRs) from several databases in a standardized environment. The main differences among the available databases concern coordinate systems, sound source stimuli, sampling frequencies and other important specifications. The repository is organized so as to consider all these differences. The structure of our repository is an improvement with respect to the MARL-NYU data format, born as an attempt to unify HRIR databases. The introduced information supports flexible analysis and synthesis processes and robust headphone equalization.
The paper gives an overview of a number of tools for the analysis and synthesis of head-related t... more The paper gives an overview of a number of tools for the analysis and synthesis of head-related transfer functions (HRTFs) that we have developed in the past four years at the Department of Information Engineering, University of Padova, Italy. The main objective of our study in this context is the progressive development of a collection of algorithms for the construction of a totally synthetic personal HRTF set replacing both cumbersome and tedious individual HRTF measurements and the exploitation of inaccurate non-individual HRTF sets. Our research methodology is highlighted, along with the multiple possibilities of present and future research offered by such tools.
IEEE ... International Conference on Rehabilitation Robotics : [proceedings], 2011
This paper reports on an ongoing research collaboration between the University of Padua and the U... more This paper reports on an ongoing research collaboration between the University of Padua and the University of California Irvine, on the use of continuous auditory-feedback in robot-assisted neurorehabilitation of post-stroke patients. This feedback modality is mostly underexploited in current robotic rehabilitation systems, that usually implement very basic auditory feedback interfaces. The results of this research show that generating a proper sound cue during robot assisted movement training can help patients in improving engagement, performance and learning in the exercise.
International Journal of Pervasive Computing and Communications, 2014
Purpose: The paper presents a system for customized binaural audio delivery based on the extracti... more Purpose: The paper presents a system for customized binaural audio delivery based on the extraction of relevant features from a 2-D representation of the listener’s pinna. Design/methodology/approach: The most significant pinna contours are extracted by means of multi-flash imaging, and they provide values for the parameters of a structural head-related transfer function (HRTF) model. The HRTF model spatializes a given sound file according to the listener’s head orientation, tracked by sensor-equipped headphones, with respect to the virtual sound source. Findings: A preliminary localization test shows that the model is able to statically render the elevation of a virtual sound source better than non-individual HRTFs. Research limitations/implications: Results encourage a deeper analysis of the psychoacoustic impact that the individualized HRTF model has on perceived elevation of virtual sound sources. Practical implications: The model has low complexity and is suitable for implementation on mobile devices. The resulting hardware/software package will hopefully allow an easy and low-tech fruition of custom spatial audio to any user. Originality/value: We show that custom binaural audio can be successfully deployed without the need of cumbersome subjective measurements.
2010 IEEE International Workshop on Multimedia Signal Processing, 2010
This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D... more This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D sound rendering. Following a structural approach, we aim at constructing a model for PRTF synthesis which allows to control separately the evolution of ear resonances and spectral notches through the design of two distinct filter blocks. Taking such model as endpoint, we propose a method based on the McAulay-Quatieri partial tracking algorithm to extract the frequencies of the most important spectral notches. Ray-tracing analysis performed on the so obtained tracks reveals a convincing correspondence between extracted frequencies and pinna geometry of a bunch of subjects.
2013 IEEE 15th International Workshop on Multimedia Signal Processing (MMSP), 2013
ABSTRACT The contribution of the external ear to the head-related transfer function (HRTF) heavil... more ABSTRACT The contribution of the external ear to the head-related transfer function (HRTF) heavily depends on the listener’s unique anthropometry. In particular, the shape of the most prominent contours of the pinna defines the frequency location of the HRTF spectral notches along the elevation of the sound source. This paper addresses the issue of automatically estimating the location of pinna edges starting from a set of pictures produced by a multi-flash imaging device. A basic image processing algorithm designed to obtain the principal edges and their distance from the ear canal entrance is described. The effectiveness of the developed hardware and software is preliminarily evaluated on a small number of test subjects.
The Journal of the Acoustical Society of America, 2015
The aim of this letter is to address a little understood question in sound source localization: C... more The aim of this letter is to address a little understood question in sound source localization: Can the distance of a near sound source affect our own perception of its elevation? The issue is studied by means of an objective analysis of a database of distance-dependent head-related transfer functions (HRTFs) of a KEMAR (Knowles Electronic Manikin for Acoustic Research) mannequin with different pinnae on a dense spatial grid. Iso-directional HRTFs are compared through spectral error metrics; results indicate significant distance-dependent HRTF modifications due to the pinna occur when the source is close to the interaural axis.
This paper addresses the problem of modeling head-related transfer functions (HRTFs) for 3-D audi... more This paper addresses the problem of modeling head-related transfer functions (HRTFs) for 3-D audio rendering in the front hemisphere. Following a structural approach, we build a model for real-time HRTF synthesis which allows to control separately the evolution of different acoustic phenomena such as head diffraction, ear resonances, and reflections through the design of distinct filter blocks. Parameters to be fed to the model are both derived from mean spectral features in a collection of measured HRTFs and anthropometric features of the specific subject (taken from a photograph of his/her outer ear), hence allowing model customization. Visual analysis of the synthesized HRTFs reveals a convincing correspondence between original and reconstructed spectral features in the chosen spatial range. Furthermore, a possible experimental setup for dynamic psycho acoustical evaluation of such model is depicted.
This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D... more This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D sound rendering. Following a structural approach, we aim at constructing a model for PRTF synthesis which allows to control separately the evolution of ear resonances and spectral notches through the design of two distinct filter blocks. Taking such model as endpoint, we propose a method based on the McAulay-Quatieri partial tracking algorithm to extract the frequencies of the most important spectral notches. Ray-tracing analysis performed on the so obtained tracks reveals a convincing correspondence between extracted frequencies and pinna geometry of a bunch of subjects.
Purpose: The paper presents a system for customized binaural audio delivery based on the extracti... more Purpose: The paper presents a system for customized binaural audio delivery based on the extraction of relevant features from a 2-D representation of the listener’s pinna.
Design/methodology/approach: The most significant pinna contours are extracted by means of multi-flash imaging, and they provide values for the parameters of a structural head-related transfer function (HRTF) model. The HRTF model spatializes a given sound file according to the listener’s
head orientation, tracked by sensor-equipped headphones, with respect to the virtual sound source.
Findings: A preliminary localization test shows that the model is able to statically render the elevation of a virtual sound source better than non-individual HRTFs.
Research limitations/implications:
Results encourage a deeper analysis of the psychoacoustic impact that the individualized HRTF model has on perceived elevation of virtual sound sources.
Practical implications: The model has low complexity and is suitable for implementation on mobile devices. The resulting hardware/software package will hopefully allow an easy and low-tech fruition of custom spatial audio to any user.
Originality/value: We show that custom binaural audio can be successfully deployed without the need of cumbersome subjective measurements.
This paper considers the problem of 3-D sound rendering in the near field through a low-order HRT... more This paper considers the problem of 3-D sound rendering in the near field through a low-order HRTF model. Here we concentrate on diffraction effects caused by the human head which we model as a rigid sphere. For relatively close source distances there already exists an algorithm that gives a good approximation to analytical spherical HRTF curves; yet, due to excessive
Advanced models for 3D audio rendering are increasingly needed in the networked electronic media ... more Advanced models for 3D audio rendering are increasingly needed in the networked electronic media world, and play a central role within the strategic research objectives identified in the NEM research agenda. This paper presents a model for sound spatialization which includes additional features with respect to existing systems, being parametrized according to anthropometric information of the user, and being based
Generalized head-related transfer functions (HRTFs) represent a cheap and straightforward mean of... more Generalized head-related transfer functions (HRTFs) represent a cheap and straightforward mean of providing 3D rendering in headphone reproduction. However, they are known to produce evident sound localization errors, including incorrect perception of elevation, front-back reversals, and lack of externalization, especially when head tracking is not utilized in the reproduction . Therefore, individual anthropometric features have a key role in characterizing HRTFs. On the other hand, HRTF measurements on a significant number of subjects are both expensive and inconvenient. This short paper briefly presents a structural HRTF model that, if properly rendered through a proposed hardware (wireless headphones augmented with motion and vision sensors), can be used for an efficient and immersive sound reproduction. Special care is reserved to the contribution of the external ear to the HRTF: data and results collected to date by the authors allow parametrization of the model according to in...
2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2014
A novel approach to the selection of generic head-related transfer functions (HRTFs) for binaural... more A novel approach to the selection of generic head-related transfer functions (HRTFs) for binaural audio rendering through headphones is formalized and described in this paper. A reflection model applied to the user's ear picture facilitates extraction of the relevant anthropometric cues that are used for selecting two HRTF sets in a database fitting that user, whose localization performances are evaluated in a complete psychoacoustic experiment. The proposed selection increases the average elevation performances of 17% (with a peak of 34%) with respect to generic HRTFs from an anthropomorphic mannequin. It also significantly enhances externalization and reduces the number of up/down reversals.
2013 18th International Conference on Digital Signal Processing (DSP), 2013
A novel approach to the modeling of head-related transfer functions (HRTFs) for binaural audio re... more A novel approach to the modeling of head-related transfer functions (HRTFs) for binaural audio rendering is formalized and described in this paper. Mixed structural modeling (MSM) can be seen as the generalization and extension of the structural modeling approach first defined by Brown and Duda back in 1998. Possible solutions for building partial HRTFs (pHRTFs) of the head, torso, and pinna of a specific listener are first described and then used in the construction of two possible mixed structural models of a KEMAR mannequin. Thanks to the flexibility of the MSM approach, an exponential number of solutions for building custom binaural audio displays can be considered and evaluated, the final aim of the process being the achievement of a HRTF model fully customizable by the listener.
This paper proposes a repository for the organization of full-and partial-body Head-Related Impul... more This paper proposes a repository for the organization of full-and partial-body Head-Related Impulse Responses (HRIRs/pHRIRs) and Headphone Impulse Responses (HpIRs) from several databases in a standardized environment. The main differences among the available databases concern coordinate systems, sound source stimuli, sampling frequencies and other important specifications. The repository is organized so as to consider all these differences. The structure of our repository is an improvement with respect to the MARL-NYU data format, born as an attempt to unify HRIR databases. The introduced information supports flexible analysis and synthesis processes and robust headphone equalization.
The paper gives an overview of a number of tools for the analysis and synthesis of head-related t... more The paper gives an overview of a number of tools for the analysis and synthesis of head-related transfer functions (HRTFs) that we have developed in the past four years at the Department of Information Engineering, University of Padova, Italy. The main objective of our study in this context is the progressive development of a collection of algorithms for the construction of a totally synthetic personal HRTF set replacing both cumbersome and tedious individual HRTF measurements and the exploitation of inaccurate non-individual HRTF sets. Our research methodology is highlighted, along with the multiple possibilities of present and future research offered by such tools.
IEEE ... International Conference on Rehabilitation Robotics : [proceedings], 2011
This paper reports on an ongoing research collaboration between the University of Padua and the U... more This paper reports on an ongoing research collaboration between the University of Padua and the University of California Irvine, on the use of continuous auditory-feedback in robot-assisted neurorehabilitation of post-stroke patients. This feedback modality is mostly underexploited in current robotic rehabilitation systems, that usually implement very basic auditory feedback interfaces. The results of this research show that generating a proper sound cue during robot assisted movement training can help patients in improving engagement, performance and learning in the exercise.
International Journal of Pervasive Computing and Communications, 2014
Purpose: The paper presents a system for customized binaural audio delivery based on the extracti... more Purpose: The paper presents a system for customized binaural audio delivery based on the extraction of relevant features from a 2-D representation of the listener’s pinna. Design/methodology/approach: The most significant pinna contours are extracted by means of multi-flash imaging, and they provide values for the parameters of a structural head-related transfer function (HRTF) model. The HRTF model spatializes a given sound file according to the listener’s head orientation, tracked by sensor-equipped headphones, with respect to the virtual sound source. Findings: A preliminary localization test shows that the model is able to statically render the elevation of a virtual sound source better than non-individual HRTFs. Research limitations/implications: Results encourage a deeper analysis of the psychoacoustic impact that the individualized HRTF model has on perceived elevation of virtual sound sources. Practical implications: The model has low complexity and is suitable for implementation on mobile devices. The resulting hardware/software package will hopefully allow an easy and low-tech fruition of custom spatial audio to any user. Originality/value: We show that custom binaural audio can be successfully deployed without the need of cumbersome subjective measurements.
2010 IEEE International Workshop on Multimedia Signal Processing, 2010
This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D... more This paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D sound rendering. Following a structural approach, we aim at constructing a model for PRTF synthesis which allows to control separately the evolution of ear resonances and spectral notches through the design of two distinct filter blocks. Taking such model as endpoint, we propose a method based on the McAulay-Quatieri partial tracking algorithm to extract the frequencies of the most important spectral notches. Ray-tracing analysis performed on the so obtained tracks reveals a convincing correspondence between extracted frequencies and pinna geometry of a bunch of subjects.
2013 IEEE 15th International Workshop on Multimedia Signal Processing (MMSP), 2013
ABSTRACT The contribution of the external ear to the head-related transfer function (HRTF) heavil... more ABSTRACT The contribution of the external ear to the head-related transfer function (HRTF) heavily depends on the listener’s unique anthropometry. In particular, the shape of the most prominent contours of the pinna defines the frequency location of the HRTF spectral notches along the elevation of the sound source. This paper addresses the issue of automatically estimating the location of pinna edges starting from a set of pictures produced by a multi-flash imaging device. A basic image processing algorithm designed to obtain the principal edges and their distance from the ear canal entrance is described. The effectiveness of the developed hardware and software is preliminarily evaluated on a small number of test subjects.
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Papers by Simone Spagnol
Design/methodology/approach: The most significant pinna contours are extracted by means of multi-flash imaging, and they provide values for the parameters of a structural head-related transfer function (HRTF) model. The HRTF model spatializes a given sound file according to the listener’s
head orientation, tracked by sensor-equipped headphones, with respect to the virtual sound source.
Findings: A preliminary localization test shows that the model is able to statically render the elevation of a virtual sound source better than non-individual HRTFs.
Research limitations/implications:
Results encourage a deeper analysis of the psychoacoustic impact that the individualized HRTF model has on perceived elevation of virtual sound sources.
Practical implications: The model has low complexity and is suitable for implementation on mobile devices. The resulting hardware/software package will hopefully allow an easy and low-tech fruition of custom spatial audio to any user.
Originality/value: We show that custom binaural audio can be successfully deployed without the need of cumbersome subjective measurements.
Design/methodology/approach: The most significant pinna contours are extracted by means of multi-flash imaging, and they provide values for the parameters of a structural head-related transfer function (HRTF) model. The HRTF model spatializes a given sound file according to the listener’s
head orientation, tracked by sensor-equipped headphones, with respect to the virtual sound source.
Findings: A preliminary localization test shows that the model is able to statically render the elevation of a virtual sound source better than non-individual HRTFs.
Research limitations/implications:
Results encourage a deeper analysis of the psychoacoustic impact that the individualized HRTF model has on perceived elevation of virtual sound sources.
Practical implications: The model has low complexity and is suitable for implementation on mobile devices. The resulting hardware/software package will hopefully allow an easy and low-tech fruition of custom spatial audio to any user.
Originality/value: We show that custom binaural audio can be successfully deployed without the need of cumbersome subjective measurements.