Ideal-observer model of human sound localization of sources with unknown spectrum

Abstract Localization of a sound source is in essence the act of decoding the directional information with which the sound was endowed by the head and ears upon measurement by the cochlea. Yet, as the source’s directional signature is conflated with the spectral characteristics of the source and the...

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Main Authors: Jonas Reijniers, Glen McLachlan, Bart Partoens, Herbert Peremans
Format: Article
Language:English
Published: Nature Portfolio 2025-03-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-91001-3
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author Jonas Reijniers
Glen McLachlan
Bart Partoens
Herbert Peremans
author_facet Jonas Reijniers
Glen McLachlan
Bart Partoens
Herbert Peremans
author_sort Jonas Reijniers
collection DOAJ
description Abstract Localization of a sound source is in essence the act of decoding the directional information with which the sound was endowed by the head and ears upon measurement by the cochlea. Yet, as the source’s directional signature is conflated with the spectral characteristics of the source and the latter is often not known to the listener, this directional signature may be obscured, hampering localization. Current localization models generally avoid this problem by considering sources whose spectrum is known to the listener. In this paper, we investigate how an ideal-observer would deal with this uncertainty of the source: by means of a prior on the source spectrum built from previous experiences. To this end, an ecologically valid prior was constructed from databases of environmental sounds and speech. Incorporation of this prior allowed to explain the results of a localization experiment in which the stimulus was varied, without any parameter fitting. It was shown that if the spectrum of the source deviates too much from those of real-world environments, this results in localization errors, because the source does not fit the prior used by the listener. Moreover, it seems that the binaural spectral gradient contains the relevant spectral information and that the ipsilateral side has more weight in the decision. We could not corroborate the experimental indication that only the positive spectral gradient values are used for localization. Finally, the model including the ecologically valid prior was also better in explaining the experimental data on localization of invariably flat spectrum stimuli, allowing for the possibility that human listeners may rather use a multi-purpose than a situation-specific spectral prior.
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spelling doaj-art-2d1fa6ee33a343c68fbd5630fd1f57792025-08-20T02:01:35ZengNature PortfolioScientific Reports2045-23222025-03-0115111110.1038/s41598-025-91001-3Ideal-observer model of human sound localization of sources with unknown spectrumJonas Reijniers0Glen McLachlan1Bart Partoens2Herbert Peremans3Department of Engineering Management, Universiteit AntwerpenDepartment of Engineering Management, Universiteit AntwerpenDepartment of Physics, Universiteit AntwerpenDepartment of Engineering Management, Universiteit AntwerpenAbstract Localization of a sound source is in essence the act of decoding the directional information with which the sound was endowed by the head and ears upon measurement by the cochlea. Yet, as the source’s directional signature is conflated with the spectral characteristics of the source and the latter is often not known to the listener, this directional signature may be obscured, hampering localization. Current localization models generally avoid this problem by considering sources whose spectrum is known to the listener. In this paper, we investigate how an ideal-observer would deal with this uncertainty of the source: by means of a prior on the source spectrum built from previous experiences. To this end, an ecologically valid prior was constructed from databases of environmental sounds and speech. Incorporation of this prior allowed to explain the results of a localization experiment in which the stimulus was varied, without any parameter fitting. It was shown that if the spectrum of the source deviates too much from those of real-world environments, this results in localization errors, because the source does not fit the prior used by the listener. Moreover, it seems that the binaural spectral gradient contains the relevant spectral information and that the ipsilateral side has more weight in the decision. We could not corroborate the experimental indication that only the positive spectral gradient values are used for localization. Finally, the model including the ecologically valid prior was also better in explaining the experimental data on localization of invariably flat spectrum stimuli, allowing for the possibility that human listeners may rather use a multi-purpose than a situation-specific spectral prior.https://doi.org/10.1038/s41598-025-91001-3ideal-observersound localizationinformation theoryBayes
spellingShingle Jonas Reijniers
Glen McLachlan
Bart Partoens
Herbert Peremans
Ideal-observer model of human sound localization of sources with unknown spectrum
Scientific Reports
ideal-observer
sound localization
information theory
Bayes
title Ideal-observer model of human sound localization of sources with unknown spectrum
title_full Ideal-observer model of human sound localization of sources with unknown spectrum
title_fullStr Ideal-observer model of human sound localization of sources with unknown spectrum
title_full_unstemmed Ideal-observer model of human sound localization of sources with unknown spectrum
title_short Ideal-observer model of human sound localization of sources with unknown spectrum
title_sort ideal observer model of human sound localization of sources with unknown spectrum
topic ideal-observer
sound localization
information theory
Bayes
url https://doi.org/10.1038/s41598-025-91001-3
work_keys_str_mv AT jonasreijniers idealobservermodelofhumansoundlocalizationofsourceswithunknownspectrum
AT glenmclachlan idealobservermodelofhumansoundlocalizationofsourceswithunknownspectrum
AT bartpartoens idealobservermodelofhumansoundlocalizationofsourceswithunknownspectrum
AT herbertperemans idealobservermodelofhumansoundlocalizationofsourceswithunknownspectrum