Explanation of masking-level differences that result from interaural intensive disparities of noise.

Abstract

The detectability of a monaurally presented 500-cps signal was measured at each of several values of interaural correlation for a wide-band noise masker. The results, when expressed in terms of masking-level differences (MLD's), are in agreement with data reported by Whitmore and Wilbanks and show a function of similar form to that described by Robinson and Jeffress. Additionally, the detectability of a monaural signal was investigated as a function of the interaural intensive relations of a wide-band noise masker. The data are in agreement with results originally shown by Hirsh, and since, replicated several times. That is, detectability is greatest when the level of the noise masker at the two ears is equal, and decreases as the level of the masker at the nonsignal ear is attenuated. The data are used to estimate parameters for a simple model that attempts to account for changes in detectability that occur when a monaural signal is presented with binaural, correlated noise having an interaural level difference. The model proposes that at low external noise levels, internal noise leads to a decrease in interaural-noise correlation. Predictions from the model are in reasonable agreement with data reported previously.