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Re: AUDITORY Digest - 17 Nov 2005 to 18 Nov 2005 (#2005-233)

Dear Jont and colleagues,

there have been many long and acrimonious debates about whether or not "speech is special"
and radically different from other vocal animal communication systems or not, and I am not sure we should necessarily reignite the debate here. Speech clearly has some features that are, as far as anyone can tell, uniquely human (it expresses languages that have generative grammars, it exhibits some odd phonological phenomena like co-articulation, etc.). Bird song is very interesting, rich, intricate and highly developed, but even the most enthusiastic birdsong experts would admit that what birds do falls a long way short of "talking". Admittedly, there are many similarities between the vocalizations used by humans and those of other animals, and I personally believe that studying the processing of animal vocalizations in animal auditory nervous systems may well give you insights into the early stages of speech processing in the human auditory system. That notwithstanding, if you call animal vocalizations a form of speech you are courting some pretty fierce controversy.


Jont Allen wrote:


Are you suggesting that birds and animals cannot talk, or make music?
I doubt speech (auditory communication) is restricted to humans (it is clearly NOT uniquely human, IMO).

Nor is speech just rhythm. If you remove the sounds above or below 1500 Hz, we know that the identification (P_c) of maximum entropy sounds (the so called nonsense speech sounds) goes to 50% (this result comes from the c1930 articulation index measurements at Western Electric, and Bell Labs, once it was created).

How does your rhythm theory figure into this result?

I am not saying that some sort of rhythm plays no roll, just trying to put your comments into some perspective. What exactly would the role of rhythm be, in your view? What is the difference between "rhythm" and critical band "modulations" (within and across critical bands), commonly found in the auditory literature, for example?

Jont Allen

AUDITORY automatic digest system wrote:

There are 4 messages totalling 430 lines in this issue.


Date:    Fri, 18 Nov 2005 21:44:21 +1300
From:    Philip Dorrell <aud@xxxxxxxx>
Subject: Re: Rhythm perception (is really speech rhythm perception)

According to my "super-stimulus" theory of music=20
(http://whatismusic.info/), the primary purpose of the cortical maps=20
that respond to regular musical rhythms is to perceive the irregular=20
rhythms of speech in a time-scaling invariant manner (i.e. the same=20
rhythm at different tempos). My theory imposes an additional constraint=20
on any theory of rhythm perception, in that it requires that the=20
perception of musical rhythms must result in geometrical patterns of=20
neural activity which are more constant than is the case when perceiving=20
speech rhythms, and which have clearly defined perimeters between active=20
and inactive regions.

This theory is consistent with the incremental perception of beat,=20
because the purpose of rhythm perception must be to label the components=20
of speech rhythm as they occur, as being more or less part of a regular=20
rhythm. There is no purpose to "find" the regular beat, because in=20
general there are no regular beats in speech. It's like Fourier=20
analysis, which happens to produce a well-defined result for regular=20
repeating signals, but can be quite useful in the characterisation of=20
non-regular non-repeating signals.

The theory is also consistent with the observation that the ability to=20
perceive musical rhythms is uniquely human (since speech is uniquely huma=

Philip Dorrell.

Dr Jan Schnupp
University Laboratory of Physiology Parks Road - Oxford OX1 3PT
Tel +44-1865-272513
email: jan@xxxxxxxxxxxxxxxx