1 Laboratory for Hearing and Cognition, Psychology Department, Concordia University, 7141 Sherbrooke St. West, Montreal, Québec H4B 1R6, Canada.

A difference in fundamental frequency (?F0) between two voices provides considerable help for listeners to segregate one from the other perceptually. Past studies have found that the ?F0 benefit relies on partials of low rank. Here, we questioned whether this observation could partly be due to spectral glimpsing. Four experiments measured speech reception thresholds for a target voice against an interfering voice (experiments 1 and 2) or against buzzes (experiments 3 and 4) with flattened F0 patterns. In experiments 1 and 3, the target F0 was fixed (at 90 Hz) and the masker F0 was raised. In experiments 2 and 4, the masker F0 was fixed (at 90 Hz) and the target F0 was raised. Furthermore, the ?F0 was (1) applied uniformly across the spectrum, (2) only available in low frequencies, (3) only available in high frequencies, or (4) swapped between low and high frequencies. Results confirmed that glimpsing plays an increasing role when the masker F0 is increased. The benefit relied primarily on frequencies below 800 Hz, but this depended somewhat on the design and on the masker type. High-frequency harmonics contributed more with buzzes, and F0 inconsistencies across channels were more detrimental at large ?F0s.