Modeling comodulation masking release using an equalization cancellation mechanism

Across-filter comparisons of temporal envelopes are a general feature of auditory pattern analysis which plays an important role in extracting signals from noise backgrounds. One example where a comparison of the temporal envelope in different frequency regions can lead to a substantial facilitation of detecting a signal in noise is comodulation masking release (CMR). It has been suggested that in (monaural) across-channel processing, like in (binaural) across-ear processing, an equalization-cancellation (EC) based circuit might be an effective strategy of noise reduction. The first part of the study investigates the relation between CMR and envelope-based binaural masking level differences (BMLD), using narrowband noise maskers and classical across-channel configurations (like N0Spi, N0Sm). In the second part, a model is presented that explicitly simulates CMR whereby the EC mechanism is assumed to take place at the output of a modulation filterbank. In the case of several flanker bands, the equalization is realized effectively by averaging the flanker bands, and cancellation by subtracting the averaged representation from the signal band. A generalized version of the model is presented that considers both across-channel and within-channel contributions to signal detection in CMR.