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Journal of the Acoustical Society of America

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Dec 2000

Volume 108, Issue 6, pp. 2685-3095

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Conical radiating waves from immersed wedges

Anne-Christine Hladky-Hennion, Philippe Langlet, and Michel de Billy

J. Acoust. Soc. Am. Volume 108, Issue 6, pp. 3079-3083 (2000); (5 pages)

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The finite-element approach has previously been used, with the help of the ATILA code, to model the subsonic and supersonic waves in immersed waveguides [A. C. Hladky-Hennion et al., J. Sound Vib. 212, 265–274 (1998)]. This method has given a precise account of the experimental results and has shown the major effects. In this paper, a new representation of radiating waves is presented, leading to a simple understanding of the physical phenomenon: radiating waves are propagating with the same phase velocity on the surface of a cone, the axis of which is the wedge direction. © 2000 Acoustical Society of America.
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43.20.Hq Velocity and attenuation of acoustic waves

Seismic-like scaling regime in impulse reflection from underwater sediment

Eric Smith

J. Acoust. Soc. Am. Volume 108, Issue 6, pp. 3084-3087 (2000); (4 pages)

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A universal scaling law is known empirically to characterize the high-frequency decay of bandpassed seismic coda. An explanation advanced for this universality, based on multiple-Rayleigh scatter of nonuniform strength, is generic enough to suggest that similar scaling may apply to decay of the impulse response in other random media. A submerged sand layer is probed experimentally as a candidate for such a medium, and its incoherent acoustic impulse reflection is found to have an exponential decay regime similar to that in seismology. © 2000 Acoustical Society of America.
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43.30.Ft Volume scattering
43.30.Ma Acoustics of sediments; ice covers, viscoelastic media; seismic underwater acoustics

Psychophysical customization of directional transfer functions for virtual sound localization

John C. Middlebrooks, Ewan A. Macpherson, and Zekiye A. Onsan

J. Acoust. Soc. Am. Volume 108, Issue 6, pp. 3088-3091 (2000); (4 pages) | Cited 4 times

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The accuracy of virtual localization when using nonindividualized external-ear transfer functions can be improved by scaling the transfer functions in frequency [Middlebrooks, J. Acoust. Soc. Am. 106, 1493–1510 (1999)]. The present letter describes a psychophysical procedure by which listeners identified appropriate scale factors. The procedure ran on nonspecialized equipment, took as little as 20 min, and could be used successfully by inexperienced listeners. Scale factors obtained from the psychophysical procedure approximated factors computed from acoustical measurements from individual listeners. Roughly equivalent virtual-localization accuracy was obtained using scale factors derived from acoustical measurements, from the psychophysical procedure, or from listeners’ physical dimensions. © 2000 Acoustical Society of America.
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43.66.Pn Binaural hearing
43.66.Qp Localization of sound sources

Minimum audible angles in the horizontal and vertical planes: Effects of stimulus onset asynchrony and burst duration

Thomas Z. Strybel and Ken Fujimoto

J. Acoust. Soc. Am. Volume 108, Issue 6, pp. 3092-3095 (2000); (4 pages) | Cited 2 times

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The effects of burst duration and stimulus onset asynchrony (SOA, the onset–onset time difference) on the minimum audible angle (MAA) were measured in the horizontal and vertical planes using high-pass noise bursts. Four listeners were tested with two burst durations (10 and 50 ms) and five SOAs (25, 50, 100, 200, and 400 ms), using an adaptive paradigm. In both planes, MAAs were lowest at burst duration = 50 ms, and the MAAs decreased exponentially with SOA. Although the effect of burst duration was generally larger in the vertical plane than in the horizontal plane, the plane of presentation did not affect the relationship between SOA and MAA. © 2000 Acoustical Society of America.
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43.66.Pn Binaural hearing
43.66.Qp Localization of sound sources
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
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