ANALYTICAL EXPRESSIONS FOR THE ENVELOPE CORRELATION OF CERTAIN NARROW-BAND STIMULI

Analytical solutions are presented for the correlation between the env elopes of certain narrow-band stimuli which are typically used in bina ural research. These stimuli are either the sum of an in-phase masker and an out-of-phase signal, or they are two partially correlated noise s. Because an envelope has a nonzero mean, the solutions differ depend ing on whether the envelope correlation is expressed as the normalized cross correlation or as the normalized cross covariance (Pearson prod uct-moment correlation). The envelope correlation depends on the stati stics of the masker and the signal whereas the waveform correlation de pends on neither. This influence only disappears for the normalized en velope cross correlation provided that the correlation is close to one . In this case, the normalized envelope cross correlation is equal to the square root of the waveform correlation. The results for two parti ally correlated noise bands are also of relevance for experiments deal ing with monaural envelope discrimination and comodulation masking rel ease. (C) 1995 Acoustical Society of America.