Loudness and the binaural masking level difference

Abstract

The large threshold difference found between a low-frequency antiphasic signal, Sπ, and in-phase signal, SO, in the presence of a homophasic noise masker (NO) is referred to as the binaural masking level difference (BMLD). The magnitude of the BMLD diminishes when the antiphasic signal is increased to suprathreshold levels. The decrease in effectiveness of a 180° phase-shifted signal, at suprathreshold levels, produces a concomitant decrease in perceived loudness of the signal. This decrease in effectiveness at the higher signal levels was examined in a loudness-matching paradigm. A change in neural processing was hypothesized to account for the variation in loudness, detectability, discrimination, and identification when the signal level approached 20 dB SL.