Modeling sound-source localization in sagittal planes for human listeners

Baumgartner, Robert; Majdak, Piotr; Laback, Bernhard

doi:10.1121/1.4887447

Cited by 96 publications

(185 citation statements)

References 42 publications

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“…Initially we intended to manipulate the salience of monaural spectral shape cues that are arguably most important for sound localization within a sagittal plane (34). Monaural loudness predictions, however, revealed that smaller spectral contrasts were accompanied by a decrease in loudness at low and mid frequencies and an increase in loudness at high frequencies.…”

Section: Spectral Contrast Manipulation Affected Auditory Distance Pementioning

confidence: 99%

Asymmetries in behavioral and neural responses to spectral cues demonstrate the generality of auditory looming bias

Baumgartner

Reed

Tóth

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Studies of auditory looming bias have shown that sources increasing in intensity are more salient than sources decreasing in intensity. Researchers have argued that listeners are more sensitive to approaching sounds compared with receding sounds, reflecting an evolutionary pressure. However, these studies only manipulated overall sound intensity; therefore, it is unclear whether looming bias is truly a perceptual bias for changes in source distance, or only in sound intensity. Here we demonstrate both behavioral and neural correlates of looming bias without manipulating overall sound intensity. In natural environments, the pinnae induce spectral cues that give rise to a sense of externalization; when spectral cues are unnatural, sounds are perceived as closer to the listener. We manipulated the contrast of individually tailored spectral cues to create sounds of similar intensity but different naturalness. We confirmed that sounds were perceived as approaching when spectral contrast decreased, and perceived as receding when spectral contrast increased. We measured behavior and electroencephalography while listeners judged motion direction. Behavioral responses showed a looming bias in that responses were more consistent for sounds perceived as approaching than for sounds perceived as receding. In a control experiment, looming bias disappeared when spectral contrast changes were discontinuous, suggesting that perceived motion in distance and not distance itself was driving the bias. Neurally, looming bias was reflected in an asymmetry of late eventrelated potentials associated with motion evaluation. Hence, both our behavioral and neural findings support a generalization of the auditory looming bias, representing a perceptual preference for approaching auditory objects.auditory looming bias | electroencephalography | distance motion perception | sound externalization | head-related transfer functions I magine yourself alone in the wilderness. Suddenly, a threatening sound permeates the darkness. Is it approaching? This is a critical question when it comes to your survival because approaching objects usually pose a greater threat than receding objects (1). The phenomenon that approaching sounds are more salient than receding sounds is commonly termed "auditory looming bias." Looming bias is reflected in a broad variety of psychophysical tasks related to salience and alertness: bias in loudness-change estimates (2-4) and judgments of duration (5), improved discriminability of motion speed (6), underestimated distances for egocentrically moving (4) or bypassing sounds (7,8), and reduced reaction time for auditory (3, 9) and visual (3) targets preceded by looming sounds. In animals, looming biases result in faster learning speed during associative conditioning (10) and longer duration of attention (11). This list shows that looming bias triggers a variety of percepts across a wide range of psychoacoustic tasks. Despite its broad behavioral significance, the mechanisms underlying auditory looming bias are still poorly ...

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Section: Spectral Contrast Manipulation Affected Auditory Distance Pementioning

confidence: 99%

Asymmetries in behavioral and neural responses to spectral cues demonstrate the generality of auditory looming bias

Baumgartner

Reed

Tóth

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Since HRTFs vary substantially across listeners [11], the spectral mismatch also varies from case to case. Psychoacoustic localization experiments showed that amplitude panning in the median plane might work for some unspecified listeners, but a derivation of a general rule holding for all listeners has not been achieved [2].In this study we aim at a more systematic and objective investigation of the limitations of VBAP by applying a model of sagittal-plane sound localization for human listeners [12]. This model has been extensively evaluated in previous studies [12,13].…”

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confidence: 99%

Modeling Localization of Amplitude-Panned Virtual Sources in Sagittal Planes

Baumgartner

Majdak

2015

J. Audio Eng. Soc.

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Vector-base amplitude panning (VBAP) aims at creating virtual sound sources at arbitrary directions within multichannel sound reproduction systems. However, VBAP does not consistently produce listener-specific monaural spectral cues that are essential for localization of sound sources in sagittal planes, including the front-back and up-down dimensions. In order to better understand the limitations of VBAP, a functional model approximating human processing of spectro-spatial information was applied to assess accuracy in sagittal-plane localization of virtual sources created by means of VBAP. First, we evaluated VBAP applied on two loudspeakers in the median plane, and then we investigated the directional dependence of the localization accuracy in several three-dimensional loudspeaker arrangements designed in layers of constant elevation. The model predicted a strong dependence on listeners' individual head-related transfer functions, on virtual source directions, and on loudspeaker arrangements. In general, the simulations showed a systematic degradation with increasing polar-angle span between neighboring loudspeakers. For the design of VBAP systems, predictions suggest that spans up to 40° polar angle yield a good trade-off between system complexity and localization accuracy. Special attention should be paid to the frontal region where listeners are most sensitive to deviating spectral cues. INTRODUCTIONVector-base amplitude panning (VBAP) is a method developed to create virtual sound sources at arbitrary directions by using a multichannel sound reproduction system [1]. VBAP determines loudspeaker gains by projecting the intended virtual source direction onto a basis formed by the directions of the most appropriate pair or triplet of neighboring loudspeakers. Within that pair or triplet, the loudspeaker signals are weighted in overall level. A problem of VBAP is associated with localization errors, that is, that virtual sources can be localized at directions deviating from the intended directions [2]. In this study we applied an auditory model in order to replicate [2] and investigate the limitations of VBAP with respect to sound localization.We use the interaural-polar coordinate system shown in Fig. 1 to distinguish different aspects of sound localization. In the lateral-angle dimension (left-right), VBAP introduces interaural differences in level (ILD) and time (ITD) and thus, perceptually relevant localization cues [3]. In the polar-angle dimension, monaural spectral features at high robert.baumgartner@oeaw.ac.at; piotr@majdak.com Localization in the polar-angle dimension (i.e., in sagittal planes) is based on a monaural learning process in which spectral features, that are characteristic for the listener's morphology, are related to certain directions [5]. Due to the monaural processing, the use of spectral features can be disrupted by spectral irregularities superimposed by the source spectrum [6]. The use of spectral features is limited to high frequencies (above around 0.7 kHz) because the s...

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“…Note that in contrast to [22], who used absolute spectral average, our spectral distortion was based on standard deviation in order to obtain a metric robust against the confounding effect of broadband differences between HRTFs. Also note that the model from [4], while showing good predictive power for normal-hearing listeners, was not applied in our study because it has neither been calibrated nor applied to hearingimpaired listeners yet. Finally, pairs of conditions were compared by means of the spatial correlation analysis [23].…”

Section: Hrtf Evaluationmentioning

confidence: 99%

“…HRTFs can be used for many purposes, e.g., for models of spatial hearing [4][5][6], for fitting of hearing aids [7,8], and for presenting virtual binaural audio signals via headphones in socalled virtual auditory displays [9,10]. As HRTFs depend on the individual geometry of the listener's head and ear, HRTFs are listener-specific [11].…”

Section: Introductionmentioning

confidence: 99%

A framework for geometry acquisition, 3-D printing, simulation, and measurement of head-related transfer functions with a focus on hearing-assistive devices

Harder

Paulsen

Larsen

et al. 2016

Computer-Aided Design

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Individual head-related transfer functions (HRTFs) are essential in applications like fitting hearing-assistive devices (HADs) for providing accurate sound localization performance. Individual HRTFs are usually obtained through intricate acoustic measurements. This paper investigates the use of a three-dimensional (3D) head model for acquisition of individual HRTFs. Two aspects were investigated; whether a 3D-printed model can replace measurements on a human listener and whether numerical simulations can replace acoustic measurements. For this purpose, HRTFs were acoustically measured for four human listeners and for a 3D printed head model of one of these listeners. Further, HRTFs were simulated by applying the finite element method to the 3D head model. The monaural spectral features and spectral distortions were very similar between re-measurements and between human and printed measurements, however larger deviations were observed between measurement and simulation. The binaural cues were in agreement among all HRTFs of the same listener, indicating that the 3D model is able to provide localization cues potentially accessible to HAD users. Hence, the pipeline of geometry acquisition, printing, and acoustic measurements or simulations, seems to be a promising step forward towards in-silico design of HADs.

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Modeling sound-source localization in sagittal planes for human listeners

Cited by 96 publications

References 42 publications

Asymmetries in behavioral and neural responses to spectral cues demonstrate the generality of auditory looming bias

Asymmetries in behavioral and neural responses to spectral cues demonstrate the generality of auditory looming bias

Modeling Localization of Amplitude-Panned Virtual Sources in Sagittal Planes

A framework for geometry acquisition, 3-D printing, simulation, and measurement of head-related transfer functions with a focus on hearing-assistive devices

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