Change in envelope beats as a possible cue in comodulation masking release (CMR)

The detection advantage associated with masker envelope coherence across frequency has typically been described in terms of comparisons of information across auditory channels. More recently it has been suggested that analysis of the output of a wider initial filter, similar to that suggested for the TMTF, can account for the data [B. G. Berg, J. Acoust. Soc. Am. 100, 1013-1023 (1996)]. This approach suggests that a change in envelope beats could serve as the cue to the addition of a pure-tone signal. Data are presented here for the detection of a tone added to multiple maskers with coherent envelopes. In one condition a change in envelope beats was an accurate potential cue, whereas in others the change was too unreliable to serve as an indicator of the presence of the signal. All conditions employing maskers with coherent envelopes produced very similar thresholds, and all showed improved sensitivity over the case of detecting a signal added to a single masker centered on the signal frequency. Results are interpreted as evidence that a change in envelope beats does not form the basis of detection in CMR.