Binaural Detection of Single Frequency Signals in the Presence of Noise

Abstract

It is well known that when signal and noise sources occupy different spacial positions, detection of the signal is influenced by the orientation of the observer. This paper presents a study of these and related factors as they affect the detectability of single frequency signals using a binaural transmission system. An adjustable-rate pulse-tone method of signal presentation was employed. The two microphones were supported in free space both with and without an artificial head. For the former, various “heads” were used to provide “interaural” separations of 2.5–13 in., while for the latter, where phase differences alone are present, data were taken for linear and rotational separations of the microphones. The results indicate that over-all detectability is a function of the combined binaural phase relationships of both signal and noise and of the monaural intensity relationship of the two signals at the ear having the higher signal-to-noise ratio. In agreement with other studies, the importance of phase differences was found limited to frequencies below about 2000 cps while the importance of pressure-level differences increased as a function of frequency above about 250 cps.