Effects of frequency, increment and decrement duration, and pedestal duration on the detection of increments and decrements in sinusoids.

Abstract

Thresholds for detection of increments and decrements in level of sinusoidal signals were measured as a function of signal duration (10, 20, or 200 ms), pedestal duration before the signal (10, 200 ms, or pedestal on continuously) and frequency (250, 1000, and 4000 Hz). Pedestal duration was varied to study adaptation effects and signal duration was varied to study temporal integration. The sinusoids were presented in a background noise intended to mask spectral splatter. Seven normal‐hearing subjects were used. Thresholds improved with increasing frequency and with increased duration for both increments and decrements. Increasing the pedestal duration before the increment from 10 to 200 ms generally improved the threshold for increment durations of 10 and 20 ms but not for an increment duration of 200 ms. When the pedestal was on continuously, distinct adaptation occurred at 4000 Hz; the pedestal appeared to fade away. However, this did not greatly affect increment thresholds, except for a slight improvement for the increment duration of 200 ms. Decrement thresholds generally became worse when the pedestal was on continuously. The results are discussed in terms of the effects of adaptation and temporal integration.