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Re: phoneme recognition and stimulus length

     In papers of the 1970s, Dom Massaro (in several papers) and Dave
Sparks both showed interference (drop in percent correct) in pitch
identification of tones just above a threshold difference apart by a
delayed following tone of intermediate frequency.   Performance improved to
an asymptotic level (but not to unmasked level) a with an ISI of 250 to 250
ms.  Others [Barry Leshowitz & Ed Cudahy,  (several papers in 1970s), and a
paper by Chuck Watson & Bill Wroton (1980s)] measured delta-F threshold as
a function of masker delay.  At most, best, threshold performance was
elevated out to approximately 110 ms.  I am not sure that backward
recognition masking is necessarily all that relevant to what is being
    Target tone duration is relevant to backward recognition masking.  Don
Ronken (early 70s) found a type of backward recognition masking when
examining the frequency DL for brief tones - a trailing tone interfered
with performance, but a preceding tone, if anything, improved
performance.  Finally, remember that the spectral bandwidth of stimulus is
an inverse function of duration, and the perception of brief segments of
tones are heard as clicks, tone pips, and finally as tones when duration is
increased.  If dealing with brief stimuli, Roy Patterson's work on minimum
duration for different types of recognition is also definitely
relevant.  However, the questions being discussed seem to be about
syllable-length stimuli, and thus time parameters that are longer than
those in the literature I have tried to summarize.
  Dick Pastore

At 05:39 PM 3/19/01 +0100, you wrote:
On Mon, 19 Mar 2001, Jont Allen wrote:

> I dont know if this is what you are getting at, but have you looked at the
> paper by Sadaoki Furui "On the role of spectral transitions for speech
> JASA, Oct. 1986, page 1016+
It partly answers my questions, as they used truncated syllables as
stimuli. But I would be more interested in the other direction:
is there any additional gain in recognition performace if we use stimuli
LONGER than a syllable?
What made me wonder about this is the "backwards recognition masking"
experiments of Massaro (unfortunately, I don't have the original papers,
only a half-page review in a Ph.D. thesis by Brian Kingsbury). Their
results say that masking has no effect if the target is longer than a
syllable or if there is at least a syllable-long silent interval between
the target and the masker. I would
need a reinforcement of these results, but possibly from the opposite
direction (i.e. not how recognition deteriorates from backwards masking
but how recognition improves from "forward helping" - so to say).

               Laszlo Toth
        Hungarian Academy of Sciences         *
  Research Group on Artificial Intelligence   *   "Failure only begins
     e-mail: tothl@inf.u-szeged.hu            *    when you stop trying"
     http://www.inf.u-szeged.hu/~tothl        *
Richard E. Pastore
Professor of Psychology and Linguistics
Binghamton University (SUNY University Center)
Binghamton, NY 13902-6000