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Re: Masking release due to the pitch-based grouping?

Dear List,

Please note the following sorely neglected article, which shows that when one hears a twelve-component uniform-amplitude harmonic complex in cosine phase in which a single component has been shifted out of cosine phase, the singular component segregates from the complex. At the same time, however, the pitch of the fundamental does not seem to be affected. The article also shows that if one passes the waveform of such a complex through a square-root or cubic-root
compressive transformation, the spectrum of the resulting waveform has a peak at the frequency of the singular component.

author = {Kubovy, M and Jordan, R},
title = {Tone-segregation by phase: On the phase sensitivity of the single ear},
journal = {Journal of the Acoustical Society of America},
volume = 66,
number = 1,
pages = {100--106},
year = 1979,
annote = {"This tone-segregation by phase raises doubts concerning several current theories of pitch perception. (…) Insofar as these results support temporal fine-structure theories of pitch perception, they are incompatible with the theories of pitch perception we cited at the beginning of this paper (Goldstein, 1973; Terhardt, 1973; Wightman 1973b)." See summary in http://www.zainea.com/deutch.htm },

Some aspects of this work were followed up in:

author = {Jane Elizabeth Daniel},
title = {Detecting spectral and temporal differences in the harmonic complex},
school = {Rutgers University, New Brunswick, NJ},
year = 1986,
note = {available from Rutgers's Library of Science and Medicine, BF.D184 1986},

I haven't seen Gockel et al.'s paper yet, but from Chen-Gia's description, this early work is germane to this issue.

Date: Thu, 15 Jan 2004 08:47:02 -0500
From: chen-gia tsai <tsai.cc@LYCOS.COM>
Subject: Masking release due to the pitch-based grouping?

…Recently I read a paper about the correlation between the crest factor and masking.

H. Gockel et al. (2003). Louder sounds can produce less forward masking: effects of component phase in complex tones, JASA 114:978-990.

Gockel and colleagues synthesized complex tones composed of unresolved harmonics, which were added either in cosine phase (CPH), giving a large crest factor, or in random phase (RPH), giving a smaller crest factor. The results indicated that CPH tones are louder and produce less forward masking than RPH tones. Thus, it cannot be the case that loudness and forward masking are determined by the same peripheral processes, such as the level of excitation or neural activity. Gockel and colleagues suggested that the representation of these sounds in the auditory system may be affected by at least two processes: fast-acting cochlear compression and suppression.

I am thinking about an alternative explanation of this effect. I synthesized several complex tones composed of unresolved harmonics. They have the same spectrum but various degrees of the crest factor due to different phase relationships of their harmonics. I find that both loudness and pitch strength decrease with the crest factor.

Assuming that unresolved harmonics at n*F0 are better grouped as the pitch strength of F0 increases, CPH is the least effective forward masker because its components are best grouped.
In my opinion the interesting effect reported in [Gockel et al. 2003] just highlights the importance of auditory scene analysis.
Chen-Gia Tsai
Ph.D Musicology, Humboldt University Berlin
Professor Michael Kubovy
University of Virginia
Department of Psychology
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