Binaural detection with spectrally nonoverlapping signals and maskers

Thresholds were measured for diotic tonal signals masked by interaurally delayed bands of Gaussian noise. When the signal frequency was 525 Hz, the spectrum of the masker was either below (highest frequency, 450 Hz) or above (lowest frequency, 600 Hz) the frequency of the signal. With a 450-Hz signal, the spectrum of the masker was always above the signal frequency (lowest frequency, 600 Hz). Signals had a 250-ms duration and were temporally centered within 300-ms-long maskers. The spectrum level of the maskers was 60 dB. Masked thresholds obtained in all three conditions varied sinusoidally with the interaural delay of the masker. The periodicities within the data were close to, but not identical with, the periodicities of the signals (not the maskers). This outcome is discussed in terms of (1) auditory distortion products stemming from interactions within the masking bands of noise [cf. van der Heijden and Kohlrausch, J. Acoust. Soc. Am. 98, 3125–3134 (1995)], and (2) binaural models incorporating internal delay mechanisms. It is shown that using such spectrally nonoverlapping signals and maskers can help test interesting hypotheses concerning binaural models. [Work supported by Grant No. 5 RO1 DC00234-13 from the National Institute of Deafness and other Communication Disorders, NIH.]