Are two ears necessary for localization of sound sources on the median plane?

Hebrank, John H.; Wright, Donald

doi:10.1121/1.1903351

Cited by 66 publications

(34 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other studies also indicated that spectral notches play a role in sound localization (e.g., Hebrank and Wright 1974;Watkins 1978). For example, Hebrank and Wright (1974) demonstrated that the illusion of an increase in sound elevation could be induced by shifting a spectral notch in the stimulus spectrum toward higher frequencies.…”

Section: Comparison To Other Studiesmentioning

confidence: 95%

Bayesian reconstruction of sound localization cues from responses to random spectra

Hofman

Opstal

2002

Biological Cybernetics

View full text Add to dashboard Cite

The directionally sensitive acoustics of the pinnae enable humans to perceive the up-down and front-back direction of sound. This mechanism complements another, independent mechanism that derives sound-source azimuth from interaural difference cues. The pinnae effectively add direction-dependent spectral notches and peaks to the incoming sound, and it has been shown that such features are used to code sound direction in the median plane. However, it is still unclear which of the pinna-induced features play a role in sound localization. The present study presents a method for the reconstruction of the spatially relevant features in the spectral domain. Broadband sounds with random spectral shapes were presented in rapid succession as subjects made saccadic eye movements toward the perceived stimulus locations. The analysis, which is based on Bayesian statistics, indicates that specific spectral features could be associated with perceived spatial locations. Spectral features that were determined by this psychophysical method resemble the main characteristics of the pinna transfer functions obtained from acoustic measurements in the ear canal. Despite current experimental limitations, the approach may prove useful in the study of perceptually relevant spectral cues underlying human sound localization.

show abstract

Section: Comparison To Other Studiesmentioning

confidence: 95%

Bayesian reconstruction of sound localization cues from responses to random spectra

Hofman

Opstal

2002

Biological Cybernetics

View full text Add to dashboard Cite

show abstract

“…It has been assumed that these sorts of spectral effects enable identification of the whereabouts of acoustic events at different elevations relative to the horizon. Evidence supporting this is in the form of retained localization function for complex sounds displaced on the MVP (e.g., Hebrank & Wright, 1974). In that plane, "classical" interaural differences are absent; the system relies on spectral changes that may be induced by each pinna, along with interaural spectral differences due to structural disparities between the two pinnae (Searle, Braida, Cuddy, & Davis, 1975).…”

mentioning

confidence: 99%

Available response choices affect localization of sound

Perrett

Noble

1995

Perception & Psychophysics

View full text Add to dashboard Cite

Successful replication of an experiment by Butler and Humanski (1992) showed that listeners are able to proficiently localize sources on a lateral vertical plane on the basis of interaural differences alone, When a lateral horizontal array was included in the test setup, that finding was replicated only for a broadband signal interacting with the pinna, not for ones (lowpass and pure tone) providing only interaural differences. Cross-plane errors conforming to "cones of confusion" were observed for those latter sounds. In a second experiment, response options were made more unconstrained, which clarified the nature of the cross-plane confusions. Lowpass signals from lateral vertical plane sources tend to be heard at or close to the horizon. Measurement of cue values needs to take account of the response options available to listeners, as well as signal properties.Classical theory of sound localization in space has stressed the role of the binaural system. Early research (Stevens & Newman, 1936) showed that the auditory system is sensitive to interaural time differences for lowfrequency sounds and interaural level differences for sounds of high frequency. The low-frequency cue is considered to be largely an effect of time and phase difference detection; the high-frequency cue is the result ofincreasingly sharp acoustic shadowing by the head. In classical theory, the head is assumed to be a perfect sphere, with the ears as holes located at the extremes of a diameter through the sphere (Mills, 1972). Using this model, interaural differences specify the horizontal angle of the sound source to' the left or right of the median vertical plane (MVP). Absence of difference specifies that the source is somewhere on the MVP. Such differences cannot unambiguously specify the vertical angle of the sound source relative to the horizontal plane nor, relatedly, whether it lies forward or rearward of, or above or below, the interaural axis. In normal listening conditions, and with a broadband noise signal, those aspects of spatial whereabouts seemingly not revealed by "classical" interaural differences can nonetheless be distinguished.In a recent report, Butler and Humanski (1992) presented results showing that listeners could accurately discriminate the whereabouts of sound sources displaced at 15 0 intervals in a quadrant above the interaural axisin the lateral vertical plane (LVP). Proficient performance was observed for bursts of 3-kHz highpass filtered noise. Such short wavelength signals interact withThe authors thank Bruce Stevenson for valuable advice about the design of Experiment 2.

show abstract

“…Psychophysical studies in humans have emphasized the importance of pinna-based spectral cues in resolving ambiguous binaural cues, both in the midsagittal plane (Blauert 1969;Gardner and Gardner 1973;Hebrank and Wright 1974;Oldfield and Parker 1984a;Roffler and Butler 1968), and in the horizontal plane (front-back errors) (Musicant and Butler 1984;Oldfield and Parker 1984a). Other reports have suggested that spectral cues influence sound localization even when binaural cues are not ambiguous (Butler and Musicant 1993;Musicant and Butler 1984).…”

Section: Introductionmentioning

confidence: 99%

Effects of Altering Spectral Cues in Infancy on Horizontal and Vertical Sound Localization by Adult Ferrets

Parsons

Lanyon

Schnupp

et al. 1999

Journal of Neurophysiology

View full text Add to dashboard Cite

. Effects of altering spectral cues in infancy on horizontal and vertical sound localization by adult ferrets. J. Neurophysiol. 82: 2294Neurophysiol. 82: -2309Neurophysiol. 82: , 1999. We investigated the behavioral consequences of removing the pinna and concha of the external ear bilaterally in infancy on the sound localization ability of adult ferrets. Altering spectral cues in this manner has previously been shown to disrupt the development of the neural representation of auditory space in the superior colliculus. Using broadband noise stimuli, we tested pinnae-removed ferrets and normal ferrets in three sound localization tasks. In each case, we found that both groups of animals performed significantly better when longer duration noise bursts were used. In a relative localization task, we measured the acuity with which the ferrets could discriminate between two speakers in the horizontal plane. The speakers were placed symmetrically either around the anterior midline or around a position 45°lateral to the midline. In this task, the pinnae-removed ferrets achieved very similar scores to the normal ferrets. By contrast, in another relative localization task that measured localization ability in the midsagittal plane, pinnae-removed ferrets performed less well than normals. In an absolute localization task, 12 speakers were spaced at 30°intervals in the horizontal plane at the level of the ferrets' ears. Overall, the pinnae-removed ferrets also performed poorly in this task compared with normal ferrets: they made significantly fewer correct responses, larger localization errors and more front-back errors. Both normal and pinnae-removed animals showed an improvement in performance with practice, although the pattern of improvement differed for each group. The largest improvements in localization accuracy were achieved by the pinnae-removed ferrets, particularly at the frontal positions, and their performance eventually approached that of the normal animals. Nevertheless, some intergroup differences were still present. In particular, the pinnaeremoved ferrets continued to make significantly more front-back errors than the normals. These deficits can be attributed to differences in the spectral localization cues available to the animals. Acoustical measurements showed that, compared with normal animals, the headrelated transfer functions in the horizontal plane were largely ambiguous around the interaural axis and also contained fewer locationdependent features in the midsagittal plane.

show abstract

Are two ears necessary for localization of sound sources on the median plane?

Cited by 66 publications

References 0 publications

Bayesian reconstruction of sound localization cues from responses to random spectra

Bayesian reconstruction of sound localization cues from responses to random spectra

Available response choices affect localization of sound

Effects of Altering Spectral Cues in Infancy on Horizontal and Vertical Sound Localization by Adult Ferrets

Contact Info

Product

Resources

About