Discrimination of Direction of Auditory Pulsed Doppler

Abstract

Trains of pulses were presented to the earphones of 17 trained listeners. In a given trial, two trains of pulses were presented: in one, the interval between pulses successively increased; in the other, the interval between pulses successively decreased about a constant center interval. The task of the listener was to identify the decreasing train. A wide range of conditions (center interpulse intervals from 0.17 to 45 msec; number of intervals from 3 to 255) yielded a wide range of detectable threshold slopes (from about 0.5 to 10 000 μsec per interpulse interval). Abrupt changes in Doppler sensitivity are observed in the vicinity of 60 pps for pulse trains with a small number of intervals, possibly suggesting a transition from rhythm to pitch-discrimination. The center frequency for minimum threshold slope systematically increased with a larger number of intervals. The result supports the proposition that a greater number of time markers are required for accurate frequency resolution at the higher frequencies. The minimal threshold time change from the first interpulse interval to the center interval is about 8 μsec in the vicinity of 1000 pps. [Research supported in part by the National Sciences Foundation.]