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Re: Instruction for subjects
Fatima, Bruno:
The continuity effect for glide perception seems to be auditory and
perhaps, although not necessarily, peripheral. This was shown
recently by Poppy Crum (UCBerkeley) in her dissertation work. She was
measuring detectability of probe tones after a noise burst following
a pure-tone glide and found that detectability increased when the
frequency of the probe was right on the glide trajectory cut short by
the noise. You should send your inquiries directly to her: pcrum2@xxxxxxxxxxxx
Pierre
At 08:17 AM 10/27/2005, Bruno Repp wrote:
Dear Fatima:
I found your observations interesting, although I am not really an
expert on this phenomenon. Nevertheless, the task reminds me of some
work on phoneme restoration that I did long ago.
I suspect that the reported continuity of the disrupted/masked sound
is not really auditory, or only partially so. Rather, it is a
figural completion achieved at a higher level of processing. It may
be analogous to the completition of partially hidden objects in
vision. If part of an object is obscured by another object, people
don't really "see" the obscured part, even though they perceive the
obscured object to be intact. Similarly, the disrupted/masked sound
may be perceived as a continuous auditory "object", even though
people really don't "hear" it during the masked portion.
You are asking your subjects to compare a sound which is heard in
its entirety to one that is heard only partially, and that may be
the reason for the confusion. The empirical question is what is
actually heard during the /disrupted/masked segment: Do people only
hear the masking noise, or do they also hear the masked sound? You
could try to address that question by asking subjects to compare the
disrupted test sounds with standards that have their central segment
attenuated by varying degrees. Perhaps there is a certain degree of
attenuation that best matches what subjects actually hear.
Best,
Bruno