Determination of masking-level differences in a reverberant environment

A masking-level-difference (MLD) paradigm was used to measure release from masking in a reverberant environment. The masking-level difference is specified in terms of the signal level in decibels at threshold for an experimental condition, relative to the signal level at threshold for the reference S₀N₀condition where the maskee and masker are both binaurally in phase. Two types of masking situations were used: (1) incoherent masking—a signal (pulsed tone or speech in this study) had to be detected in a noise background; (2) coherent masking—the signal and masker were derived from the same source. Bandlimited noise and speech were used in the coherent masking experiments. For both masking conditions, the MLD was found to be approximately 3 dB. Cross correlation of the late-echo structure of impulse responses taken at the left and right ears of a manikin show that the reverberant sound field is uncorrelated between the two ears. This is consistent with a 3-dB MLD result.