Newsgroups: comp.speech
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From: hill@cpsc.ucalgary.ca (David Hill)
Subject: Re: speech, non-speech discrimination
Message-ID: <CIs3oC.BI6@cpsc.ucalgary.ca>
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Organization: University of Calgary Computer Science
References: <63442@ogicse.ogi.edu>
Date: Wed, 29 Dec 1993 04:12:11 GMT
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In article <63442@ogicse.ogi.edu> ldcolton@chico.cse.ogi.edu (L Don Colton) writes:
>For my ph.d. research proficiency exam, i am interested in identifying
>speech versus non-speech (background noises, etc) in telephone
>waveforms.
[munch]
>I would very gratefully accept observations, opinions, miscellaneous
>feedback (and references!). Email me or post here, as I read this
>newsgroup religiously. Thanks much!
>
>-- 
>Don Colton               ___e     Center for Spoken Language Understanding
>ldcolton@cse.ogi.edu   _`\ <;     Oregon Graduate Institute, 20000 NW Walker Rd
>bicycle commuter______(_)/_(_)____P.O.Box 91000, Portland, OR 97291-1000

In my first follow-up, I used "rms" and "mean" to mean the same thing
(just for clarification).

There is an article in Electronics Vol. 36. No. 5 June 21st 1963 !! %^0
"Speech operates safety switch" by William C. Dersch in which the author
claims that detecting the assymetry of the voice waveform will allow the
presence of speech to be detected at -95dB signal to noise ratio.  It states
that this assymetry only shows up when (an) even harmonics is (are) phase
shifted relative to the fundamental.  I would think the assymetry was there
in the basic waveform.  It may well be enhanced by playing around with the
phase of the harmonics, and this (I seem to remember) was also the basis
of the vowel recognition in his recogniser--different amounts of assymetry
depending on the vowel--but this complicates things if the pitch is varying.

At least its a start.  Let me know how you get on.

david

-- 
david hill: hill@cpsc.ucalgary.ca	|	Imagination is more
voice: 403-282-6481, fax: 403-282-6778	|	important than knowledge.
nextmail: hill@trillium.ab.ca		|		(Albert Einstein)
