Evidence specifically favoring the equalization-cancellation theory of binaural unmasking

Three experiments investigated the roles of interaural correlation (p) and of the monaural power spectrum in the detection and discrimination of narrow-band-noise signals (462-539 Hz) in broadband maskers (0-3 kHz). The power and p of the target band were independently controlled, while the flanking noise was fixed and diotic. Experiments I and 2 involved p and power values that would be produced by specific values of signal-to-noise ratio (SNR) in the NoS pi binaural configuration. Listeners were required to discriminate different SNRs via a 2I-FC loudness-discrimination task. At low reference SNRs, changes in p fully accounted for listeners' performance,. but as reference SNR increased, additional energy in the target band played an increasing role. Experiment 2 showed that at these higher SNRs the combination of information from the power spectrum and p was superadditive and could not be explained by simple signal-detection models. The equalization-cancellation (EC) theory would explain these data using the output from interaural cancellation, Y, rather than p. Experiment 3 attempted to foil binaural processing, by fixing either p or Y across intervals. Consistent with EC theory, when Y was fixed, the contribution of the binaural system appeared negligible, while fixing p did not have this effect. (c) 2007 Acoustical Society of America.