Critical Band in Binaural Detection

In order to account for binaural improvements in detection on the basis of interaural phase shifts, or time deviations, it is necessary to assume that the “critical band” is a sinusoidlike process and that corresponding processes from the two ears interact. Support for this assumption is reported for the binaural conditions N0Sπ, NπS0, N0S0, N0Sm, and NπSm. It was found that neither interaural level nor bandwidth differences matter so long as the levels within the critical bands at the two ears are unaffected. Detection at one ear is affected only by a narrow band of frequencies at the opposite ear, thus confirming the assumption of a band-limited binaural interaction. Experiments were carried out with three different maskers: a narrow-band noise, a medium-band noise, and a medium-band noise with a gap in it. The narrow-band masker was as effective as the medium-band masker. The noise with a gap in it, however, produced a minimal release from masking when added at the nonsignal ear. These findings are discussed within the context of those of earlier investigations.