(at)

Subject: 
From:    at <REPP%ROD%YALEVMS.BITNETPSUVM.PSU.EDU>
Date:    Mon, 21 Sep 1992 11:38:00 EST

Dear Al:

    I am not so sure Al Liberman's "pre-emptiveness" hypothesis should
be taken seriously in the first place. If the speech module takes all
the auditory information it needs, how come I hear ANYTHING when I
listen to speech? You might answer: What I "hear" are the phonemes, not
the sounds they are made of. This may be so in the case of stop
consonants, whose transitory auditory correlates are difficult to
hear (and describe) as sound objects, but it is patently false in the
case of fricatives and other continuants as well as vowels, whose
auditory correlates (noises or resonances of certain timbres or
brightnesses) can be focused on relatively easily, without losing the speech
percept. Even in the case of the stop consonants, it may be argued
that we cannot describe what we hear, though we do hear the auditory
substrate.

    I would be more interested in the related question of whether
speech sound formation provides an auditory grouping principle that
competes with principles of primitive stream segregation. For example,
if the three components of a three-tone sine-wave speech analog were
accompanied by a fourth tone that moves in parallel with the second
tone but an octave higher, will listeners be able to perceive the
speech? And if they perceive the speech, will they hear it as being
accompanied by a high whistle? Alternatively, the second and fourth
tones may group to form a single complex tone, which may either impair
speech perception or perhaps give the "voice" a different quality.

    Another reservation about your proposed experiment: The information
in sine-wave speech that affords speech perception is fairly abstract
to begin with. Listeners hear the phonetic message, but they also hear
the strange whistling quality of the speech. So, what, if anything, has
been "removed" by the speech processor? The processor does not expect
pure tones, it expects formants. Therefore, any experiment using pure
tones may be dismissed as irrelevant to the issue. Moreover, to the
extent that the relevant information is the RELATIONSHIP between
several frequency-modulated resonances or tones, pre-emption of that
relationship would leave the components of the auditory signal
unaltered.

    Best regards,

    Bruno Repp
    Haskins Laboratories