Demonstrations of
Auditory Illusions and Tricks
2nd Edition
I. The Gap Transfer
Illusion
<1>
A Long Glide Tone and a Short Glide Tone Crossing Each Other.
A long, ascending glide tone and a short, descending
glide tone cross each other. The ascending tone is
2500 ms in duration, and glides from 422 to 2371 Hz.
The descending tone is 500 ms long, and glides from
1189 to 841 Hz. The glides cross each other
in the middle of the pattern at 1000 Hz and the slope
of the glides is about 1 octave/second.
The rise time and the fall time of the short glide are 10 ms and
the long glide has a rise and fall time of 500 ms.
A 'bouncing' percept is common in patterns where
two components cross each other at the same speed.
The present pattern, however, is often perceived as 'crossing'
as a whole, although the long ascending tone of the percept
often changes its movement around the crossing point.
Halpern, L. (1977).
The effect of harmonic ratio relationships on auditory stream
segregation. Unpublished research report, Psychology Department,
McGill University.
Tougas, Y. & Bregman, A.S. (1985).
The crossing of auditory streams.
Journal of Experimental Psychology:
Human Perception and Performance, 11, 788-798.
McPherson, L., Ciocca, V., & Bregman, A.(1994).
Organization in audition by similarity in rate of change:
Evidence from tracking individual frequency glides in
mixtures. Perception & Psychophysics,
55, 269-278.
<2>
A Long Continuous Glide Tone and a Short Disrupted
Glide Tone Crossing Each Other
The difference between this pattern and Demonstration <1>
is that the short descending glide tone now has a 100 ms
gap in the temporal middle. This pattern is usually
perceived veridically.
<3> The Gap Transfer Illusion
This demonstration consists of three successive patterns.
First, a short, descending glide tone is presented with a
duration of 500 ms and a rise and fall time of 10 ms.
The glide descends from 1189 to 841 Hz, and is perceived
as being continuous.
Next, one long, ascending glide tone is presented with
a 100 ms gap in the temporal middle. The longer glide
ascends from 422 to 2371 Hz and has a rise and fall time of
500 ms.
In the last pattern, the first two patterns are combined.
The two glides are perceived as crossing each other, but,
although physically present in the long glide, the gap is
perceived in the middle of the short descending tone.
Despite the difference in the physical location of the gap,
the pattern in Demonstration <2> and this pattern
are perceived as being similar.
Nakajima, Y., Sasaki, T., Kanafuka, K., Miyamoto, A.,
Remijn, G., & ten Hoopen, G. (in press).
Illusory recouplings of onsets and terminations of glide tone
components. Perception & Psychophysics.
Kanafuka, K., Tanaka, S., Nakajima, Y., & Sasaki, T. (1996).
An illusory transfer of temporal gaps between crossing tones.
Journal of the Acoustical Society of America, 100, 4, 2683.
<4> A Long Glide Tone and a Short Glide Tone
with a Common Gap Crossing Each Other
Two crossing glides with the
same features as the glides in Demonstration <1> are
presented, but both the long, ascending glide and
the short, descending glide have a temporal gap of
50 ms at the crossing point in the middle.
However, the listener perceives a relatively
continuous ascending tone. A clear gap is perceived
only in the middle of the short tone.
<5>
A Long Ascending Glide and Two Short Ascending Glides with a Common Gap
Three ascending frequency glides have a common temporal
gap of 40 ms, located in the middle of each
glide. The gap is perceived clearly, but it typically
appears as a gap in a short, ascending tone, corresponding
to the two short glides. The long glide is perceived as
relatively continuous. The gap of 40 ms is perceived
clearly in the long tone if the short glides are removed.
<6> A Long Glide Tone and a Short Glide Tone
Crossing Each Other in Opposite Phases
This stimulus pattern is identical with that in
Demonstration <1> except that the two components
have opposite phases at the crossing points.
Acoustic beats between the two components
make a kind of temporal gap of about 40 ms at the
crossing point.
This gap, which is common to both components, is
often perceived as a gap in the short component,
and the long component is perceived as relatively
continuous.
