Binaural Unmasking of Vocalic Signals

Auditory unmasking was studied in an experiment that used natural and synthetic vowel sounds as target signals. In all listening conditions, the spectrum level of the noise was constant and the noise was in phase at the two ears, while the interaural phase relations of the signals were manipulated. The results support the idea that maximal threshold shifts occur when the components of the complex signal in the 250‐ to 500‐Hz region are interaurally out of phase. However, the data do not support the idea that the magnitude of the unmasking is a simple function of fundamental frequency. Binaural unmasking of complex amplitude varying stimuli may be best accounted for by considering the amount of energy in the 250‐ to 500‐Hz band relative to the characteristic spectral maxima in the signal. Interaural phase inversions outside the 250‐ to 500‐Hz band have differential effects on unmasking depending upon the amplitude relations between the energy inside and outside this band.