Rh. Dye et al., THE EFFECT OF DISTRACTOR FREQUENCY ON JUDGMENTS OF TARGET LATERALITY BASED ON INTERAURAL DELAYS, The Journal of the Acoustical Society of America, 99(2), 1996, pp. 1096-1107
A two-dimensional stimulus-classification paradigm was used to examine
the ability of listeners to judge the laterality of an interaurally d
elayed low-frequency target component presented concurrently with a di
stracter component. Of primary interest was the effect on performance
of the frequency difference (Delta f) between the target and distracte
r. In one set of conditions, the target was fixed at 753 Hz and the di
stracter was 353, 553, 653, 703, 803, 853, 953, or 1153 Hz (fixed with
in a block of trials). In a second set of conditions, the distracter w
as fixed at 753 Hz and the target frequency was 353, 553, 653, 703, 80
3, 853, 953, or 1153 Hz. The listeners were presented with a target co
mponent with an interaural delay that varied from trial to trial, taki
ng on one of ten values, five leading to the left ear and five leading
to the right. A distracter component was simultaneously presented wit
h an interaural delay that also took on one of the same ten values. De
lays ranged from -90 to +90 mu s in 20-mu s steps. During a block of 1
00 trials, each of the possible combinations of target and distracter
delay was presented once and only once in a random order. Listeners we
re instructed to make left-right judgments based on the target delay.
Each condition was repeated ten times, and the slopes of the best line
ar boundaries between left and right responses were used to derive the
relative weights given to the target and distracter. The duration of
the signals was 200 ms. Two of the eight listeners weighted the target
heavily when the target and distracter were spectrally remote but gav
e the two components equal weight when the difference in frequency was
small. These two listeners yielded similar target weights regardless
of which component was designated as the target. One listener gave nea
rly equal weight to the target and the distracter regardless of Delta
f. Five of the listeners gave greater weight to the higher of the two
frequencies regardless of which was assigned as the target. This high-
frequency dominance is explained in terms of cross-correlation functio
ns based on the composite two-tone waveforms. (C) 1996 Acoustical Soci
ety of America.