Subject: FWD: How many sources at once ... ?
From: Kevin Austin (firstname.lastname@example.org)
Date: Fri Apr 30 2004 - 22:09:07 EDT
FWD: From AUDITORY
>Date: Fri, 30 Apr 2004 14:26:01 -0500
>From: Valeriy Shafiro <Valeriy_Shafiro@RUSH.EDU>
>Subject: Re: Computational ASA -- how many sources can humans perceive?
>From: "Maher, Rob" rmaher@ECE.MONTANA.EDU
> >It is sometimes argued that "humans can do separation, so the
>problem must be soluble." I would argue that humans do source
>_identification and tracking_ very effectively, but perhaps humans
>do not actually solve the computational _separation_ problem, in the
>sense that the individual vectors 'B', 'C', etc. are extracted in a
>neural signal processing context.
>I would like to ask a further question: Do we, in fact, know how
>many independent sound sources in a mixture humans can perceive?
>Thus far I know of only one research report where human listeners
>were asked to
>identify sound sources in a recorded "real-world" sound mixture
>(Ellis, D. P. (1996). Prediction-driven computational auditory scene
>We have been talking about this issue with Brian Gygi, and from the
>few related reports that Brian found, it appears that humans may not
>be that good in simultaneous perceiving independent sound sources.
>For instance, Jennifer Tufts and Tom Frank J. Acoust. Soc. Am. 101 ,
>3107 (1997) found that the accuracy of judging the number of talkers
>in a multitalker mixture drops considerably when there are more than
>There is also a report by David Huron (Music Perception, Vol. 19,
>No. 1 (2001) pp. 1-64., or on-line
> ) that estimating the number of musical lines in polyphonic music
>worsens considerably after 3.
>Some anecdotal evidence for this limit also comes from movie sound
>effect designers. This is a citation from Walter Murch, a renown
>sound effect artist: "There is a rule of thumb I use which is never
>to give the audience more than two-and-a-half things to think about
>aurally at any one moment. Now, those moments can shift very
>quickly, but if you take a five-second section of sound and feed the
>audience more than two-and-a-half conceptual lines at the same time,
>they can't really separate them out. There's just no way to do it,
>and everything becomes self-canceling." (cited from
>Any thoughts, comments, and references relevant to this issue are appreciated.
>Communication Disorders and Sciences
>Rush University Medical Center
>office (312) 942 - 3298
> lab (312) 942 - 3316
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