Vertical-plane sound localization probed with ripple-spectrum noise.

Full Abstract

Ripple-spectrum stimuli were used to investigate the scale of spectral detail used by listeners in interpreting spectral cues for vertical-plane localization. In three experiments, free-field localization judgments were obtained for 250-ms, 0.6-16-kHz noise bursts with log-ripple spectra that varied in ripple density, peak-to-trough depth, and phase. When ripple density was varied and depth was held constant at 40 dB, listeners' localization error rates increased most (relative to rates for flat-spectrum targets) for densities of 0.5-2 ripples/oct. When depth was varied and density was held constant at 1 ripple/oct, localization accuracy was degraded only for ripple depths > or = 20 dB. When phase was varied and density was held constant at 1 ripple/oct and depth at 40 dB, three of five listeners made errors at consistent locations unrelated to the ripple phase, whereas two listeners made errors at locations systematically modulated by ripple phase. Although the reported upper limit for ripple discrimination is 10 ripples/oct [Supin et al., J. Acoust. Soc. Am. 106, 2800-2804 (1999)], present results indicate that details finer than 2 ripples/oct or coarser than 0.5 ripples/oct do not strongly influence processing of spectral cues for sound localization. The low spectral-frequency limit suggests that broad-scale spectral variation is discounted, even though components at this scale are among those contributing the most to the shapes of directional transfer functions.

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Author information

Author/s: Macpherson, Ewan A (EA); Middlebrooks, John C (JC);

Affiliation: Kresge Hearing Research Institute, University of Michigan, 1301 East Ann Street, Ann Arbor, Michigan 48109-0506, USA. emacpher(-atsign-)umich.edu

Grants: R01DC00420 (Agency:United States NIDCD) ; T32DC00011 (Agency:United States NIDCD)

Journal and publication information

Publication Type: Journal Article; Research Support, U.S. Gov't, P.H.S.

Journal: The Journal of the Acoustical Society of America (J Acoust Soc Am), published in United States. (Language: eng)

Reference: 2003-Jul; vol 114 (issue 1) : pp 430-45

Dates: Created 2003/07/25; Completed 2003/09/26; Revised 2007/11/14;

PMID: 12880054, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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