Dd. Mccall et al., SUDDEN CHANGES IN SPECTRUM OF AN ECHO CAUSE A BREAKDOWN OF THE PRECEDENCE EFFECT, Perception & psychophysics, 60(4), 1998, pp. 593-601
The effect of changing the frequency components of an echo relative to
the sound source was examined in a two-choice discrimination task. Su
bjects sat in an anechoic chamber and discriminated the direction of t
he lag noise burst within a lead-lag pair presented over loudspeakers.
The leading noise burst was broadband, and the lagging burst was eith
er high-or low-pass filtered. On some conditions, this test burst pair
was preceded by a conditioning train of burst pairs, which also had a
broadband lead and either a high-or low-frequency lag. When the frequ
ency content of the echo was held constant across the conditioning tra
in and test burst pair, echo suppression that was built up during the
repeating train was maintained for the test burst pair, shown by the s
ubjects' poor performance in detecting the location of the lagging bur
st. By comparison, subjects had little difficulty in localizing the la
gging burst when the frequency content of the echo changed between the
conditioning train and the test burst, indicating that any buildup of
suppression during the train was broken when the lagging burst's spec
trum shifted. The data are consistent with an interpretation in which
echo suppression is temporarily broken when listeners' built-up expect
ations about room acoustics are violated.