channel asynchrony ("Eric W. Healy" )

Subject: channel asynchrony
From:    "Eric W. Healy"  <ewh(at)SC.EDU>
Date:    Wed, 12 Mar 2003 16:56:37 -0500

Hi Dave, When many frequency bands and a variety of delays are used, larger maximum delays can be tolerated (Greenberg & Arai, 1998; also see Fu & Galvin, 2001). However, as was pointed out, this does not mean that the delays are not detectable ("perceptual equivalence"). When speech-modulated tones were used in place of speech bands, and when the number of channels was limited to two (which allows for the strict isolation of the effect of asynchrony), it was difficult for us to hear 12.5 ms of cross-channel asynchrony. Twenty-five ms was clearly detectable and produced lowered intelligibility scores. Intelligibility fell toward zero at 100 ms. This holds for band pairs drawn from various regions of the speech spectrum (Healy & Bacon, 2000). Interestingly, listeners having a hearing impairment have more difficulty comparing both synchronous and asynchronous across-frequency information, suggesting that their comparison/integration mechanism may not be as robust as that of NH listeners (Healy & Bacon, 2002). Fu, Q-J, & Galvin, J.J., III. (2001). Recognition of spectrally asynchronous speech by normal-hearing listeners and Nucleus-22 cochlear implant users. JASA, 109, 1166-1172. Greenberg, S. & Arai, T. (1998). Speech intelligibility is highly tolerant of cross-channel spectral asynchrony. Joint Meeting of the ASA and the International Congress on Acoustics, Seattle, 2677-2678. Healy, E.W. & Bacon, S.P. (2000). Across-frequency timing in speech perception: Effective processing of contrasting temporal speech patterns requires proper synchronous alignment. JASA, 108, 2603(a). Healy, E.W. & Bacon, S.P. (2002). Across-frequency comparison of temporal speech information by listeners with normal and impaired hearing. JSLHR, 45, 1262-1275. Hope this helps. -Eric -- Eric W. Healy, Ph.D. Assistant Professor Department of Communication Sciences and Disorders Norman J. Arnold School of Public Health University of South Carolina Columbia, SC 29208 (803) 777-1087 voice (803) 777-3081 fax At 12:00 AM 3/12/2003, you wrote: >Date: Tue, 11 Mar 2003 12:02:43 +0000 >From: David Dorran <david.dorran(at)DIT.IE> >Subject: temporal resolution > >Hi, > >I've posted this message to the music-dsp list so apologies to anyone who >recieves it twice (should have posted it here in the first place since its >more appropriate). > >Consider the case where an audio signal is filtered into subbands and each >subband is passed through a delay (of different duration for each subband) >before recombination of subbands to produce a new signal. What would be >the maximum permissible difference between the maximum and minimum delays >so that the new signal is perceptually equivalent to the original? > >Regards, > >Dave. >------------------------------ > >Date: Tue, 11 Mar 2003 11:10:27 -0400 >From: "Dennis P. Phillips, Ph.D." <Dennis.Phillips(at)DAL.CA> >Subject: Re: temporal resolution > >Hi Dave: > >Arai & Greenberg (1998) studied speech intelligibility in samples in >which spectral slices had undergone temporal jitter of this general >kind. My recollection is that asynchronies up to (and sometimes >exceeding) 200 ms could support 50%-correct word recognition. >"Correct word recognition" is, of course, not the same thing as >"perceptual equivalence". My point is only that the Arai & Greenberg >article might be a good place to start looking for the evidence you >need. I hope that this helps. All good wishes, > >Dennis > >Arai, T., and Greenberg, S. (1998) Speech intelligibility in the >presence of cross-channel spectral asynchrony. Proc. IEEE Conf. >Acoust. Speech Signal Proc., Seattle, 933-936. >----------------------------------- >Dennis P. Phillips, Ph.D. >Hearing Research Laboratory >Professor, >Department of Psychology >Dalhousie University >Halifax, NS, Canada B3H 4J1 >Phone: (902) 494-2383 >Fax: (902) 494-6585 >E-mail: Dennis.Phillips(at)Dal.Ca >------------------------------ >Date: Tue, 11 Mar 2003 14:00:32 -0300 >From: Regis Rossi Alves Faria <regis(at)LSI.USP.BR> >Subject: Re: temporal resolution > >Hello, > >auditory system is much more sensitive to modulations of any order than >the visual system is; >during my studies with wavelet decomposition/reconstruction of >audio/musical signals, it became very clear that spectral processing >done in some >subbands produces several modulations in the audio signal, which are >sensed as effects in the sound; >I wonder what kind of effects different delays applied to subbands would >cause to the sound, causing the reconstruction to have easily recognized > >distortion/modulations even when delays are very short. > >regards, >Regis

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