Abstract:
Investigations in this laboratory demonstrated that the normalized correlation accounted well for listeners' performance in binaural tasks utilizing high-frequency stimuli for which the envelopes convey the interaural information. This outcome means that the non-zero mean of the envelopes must be included in the computation of the correlation. Due to peripheral auditory processing analogous to rectification and low-pass filtering, the ``internal'' representations of auditory stimuli have nonzero means regardless of their frequency. This study evaluated whether the normalized correlation computed subsequent to rectification and low-pass filtering could account for detection data at low and intermediate, as well as high frequencies. In a four-interval, two-alternative task, listeners detected which interval contained a tone (between 500 Hz and 2 kHz) added antiphasically to diotic, 100-Hz-wide, noise (NoS(pi)). ``Nonsignal'' intervals contained the tone added homophasically (NoSo). Performance was measured for S/Ns between -30 and +30 dB. For all S/Ns, overall level was 70 dB SPL. Normalized correlation (unlike the correlation coefficient) described performance well, as a function of S/N and center frequency. The parameters of the rectifier and low-pass filter required to describe the data will be discussed. [Supported by research Grant No. 5R01DC0210302, National Institute on Deafness and Other Communication Disorders, NIH.]