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Re: By any other name...
I have a little bit philosophical answer. You can think that the sound is
"either present or absent." What is really interesting is that the
perceptual system seems to prefer one of the solutions in some contexts.
Probably, we need an explanation at a higher level, at least in some cases.
Now, there is a case, where we definitely need such an explanation. My
colleagues and I recently reported an auditory phenomenon where a glide tone
with a real temporal gap, where there is no sound energy, can be perceived
Gerard Remijn, Yoshitaka Nakajima, and Shunsuke Tanaka, "Perceptual
completion of a sound with a short silent gap," Perception (in press).
Because the paper is still in press, I would like to show you the abstract
Listeners reported the perceptual completion of a sound in stimuli
consisting of two crossing frequency glides of unequal duration that shared
a short silent gap (40 ms or less) at their crossing point. Even though both
glides shared the gap, it was consistently perceived only in the shorter
glide, whereas the longer glide could be perceptually completed. Studies on
perceptual completion in the auditory domain reported so far have shown that
completion of a sound with a gap occurs only if the gap is filled with
energy from another sound. In the stimuli used here, however, no such
substitute energy was present in the gap, showing evidence for perceptual
completion of a sound without local stimulation ('modal' completion). The
results show that the perceptual completion of the long glide occurred under
both monaural and dichotic presentation of the gap-sharing glides, and
therefore involves central stages of auditory processing. The inclusion of
the gap in the short glide, rather than in both the long and the short
glide, is explained in terms of auditory event and stream formation.
Yoshitaka NAKAJIMA, PhD
Professor, Dept. of Acoustic Design
Fukuoka 815-8540, Japan
Telephone: +81 92 553 4558
Facsimile: +81 92 553 4520
----- Original Message -----
From: "Bruno Repp" <repp@xxxxxxxxxxxxxxxx>
Sent: Thursday, March 22, 2007 11:08 PM
Subject: Re: By any other name...
> Dear Richard:
> There is a philosophical (or methodological?) problem I've had with
> this effect for a long time: If, as you say, "the interrupting louder
> sound stimulates the same peripheral receptors that would have been
> stimulated if the sound had indeed been present", what proves that
> the sound is actually absent?
> >The auditory continuity phenomenon has been the subject of several
> >communications earlier this month, and several names of people
> >associated with this illusion were mentioned. Massimo Grassi
> >correctly stated that Vicario's name belongs on the list. He did
> >indeed observe the effect in 1960, naming it "L'effetto tunnel
> >acustico." But Miller and Licklider seem to have been the first
> >discoverers in 1950. Several other investigators, unaware of the
> >earlier publications, made their own independent discoveries. This
> >led to a multiplicity of terms describing the effect including
> >"picket fence effect," "auditory figure ground effect," and more
> >recently, "auditory continuity effect," "auditory induction," and
> >"temporal induction."
> >The communications this month seem to have limited this phenomenon
> >to the illusory continuity of steady-state tones and tone glides
> >through interruptions by a louder noise. But this phenomenon is
> >much broader: portions of any sound can be restored if the
> >interrupting louder sound stimulates the same peripheral receptors
> >that would have been stimulated if the sound had indeed been
> >present. In everyday life this effect represents a sophisticated
> >process that can restore portions of signals (including speech) if
> >they have actually been masked. This is accomplished by
> >reallocating a portion of the neural representation of the louder
> >interrupting sound for the perceptual synthesis of the fainter
> >signal. In support of this mechanism, it had been shown that when
> >illusory restoration of the fainter sound (either a tone or speech)
> >occurred, it was accompanied by a decrease in the loudness of the
> >interrupting sound [R.M. Warren et al., 1994, Auditory induction:
> >Reciprocal changes in alternating sounds. Perception and
> >Psychophysics, 55, 313-322].
> >For a review of the literature, see Chapter 6 "Perception of missing
> >sounds" in R.M. Warren, 1999, Auditory Perception: A New Analysis
> >and Synthesis, New York: Cambridge University Press (a third
> >edition is now in production by Cambridge).
> Bruno H. Repp
> Haskins Laboratories
> 300 George Street
> New Haven, CT 06511-6624
> Tel. (203) 865-6163, ext. 236
> Fax (203) 865-8963
> NOTE: I am at Rutgers University, Newark, two days each week,
> usually Wednesday and Friday, and don't read my
> Haskins e-mail on those days. To reach me at Rutgers, send
> e-mail to <repp@xxxxxxxxxxxxxxxxxxxxxx>.