ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06
2pPP3. The influence of pattern-based frequency expectations on resolving
power for components of multitone sequences.
Gary R. Kidd
Dept. of Speech and Hear. Sci., Indiana Univ., Bloomington, IN 47405
The effect of deviations from frequency expectations on resolving power
for components of tonal sequences was studied with a method similar to that
used earlier to determine the effect of temporal deviations [G. R. Kidd,
2966(A) (1994)]. In a same--different task, listeners were asked to
compare the last two of four twelve-tone patterns presented on each trial. The
first two patterns were identical and served to establish expectations from
which the third and fourth patterns could deviate. In the third pattern, the
frequency of a single ``target'' tone was lowered by either 3 or 7 semitones,
or left unchanged. The frequency change to be detected was added to the target
component in the fourth pattern on half the trials. Thresholds for this
frequency increment were estimated for each deviation condition (as defined by
the target-tone frequency used in the third pattern). Just as with deviations
from temporal expectations, deviations from frequency expectations produced
threshold increments that increased with the size of the deviation. These
findings suggest that the superior discriminability typically observed with
familiar patterns is due to the appropriate targeting of attention in frequency
and in time during pattern presentation. [Work supported by NIDCD.]