Periodicity discrimination for auditory pulse trains.

Two forms of periodicity are distinguished for auditory pulse trains in which information is coded in terms of the interval between successive pulses. Internal periodicity refers to the precision of reproducing adjacent intervals between successive pulses. External periodicity refers to the reproduction of a repeated pattern of successive pulses. Two variables were manipulated to study the discrimination of pulse trains of controlled internal and external periodicity: the number of successive presentations of a given pattern of interpulse intervals and the deviation of the intervals from strict internal periodicity. Equivalent results are obtained with both variables. Periodicity discrimination improves as the number of interpulse intervals within the pattern is increased and as the average interpulse interval is decreased. Acute periodicity discrimination is developed at high pulse frequencies with a large number of interpulse intervals. Periodicity discrimination at low pulse frequencies is relatively p...