Evidence for a cancellation mechanism in perceptual segregation by differences in fundamental frequency
John F. Culling, Gareth M. Linsmith, Tracy L. Caller · The Journal of the Acoustical Society of America · 2005
Identification of target speech material is better when it differs in fundamental frequency (F0) from interfering speech material. Two experiments tested the idea that this effect is mediated by a cancellation process that perceptually removes sound on one F0. Expt. 1 used monotonized target speech at 112.5 Hz F0 against two monotonized interferers. The F0s of the interferers were either both 112.5 Hz, both 126 Hz, or 100 and 126 Hz. Speech reception thresholds (SRTs) were about 3.5 dB lower when the two interferers shared a 126 Hz F0 than in the other two conditions, which differed by only 0.3 dB. These results are consistent with a cancellation mechanism that is able to remove sounds at only a single F0. Expt. 2 replicated and extended Expt. 1, testing whether the results were affected by the allocation of the target and interferers to particular F0s. When all sentences shared a common F0, SRTs were now 1–1.5 dB higher than when they were all different. However, all 4 SRTs for interferers sharing the same F0 (differing from that of the target by 2 or 4 semitones) were lower than all three of the SRTs for interferers with independent F0s.