Abstract:

Voice onset time (VOT) is a temporal cue that can distinguish consonants such as /d/ from /t/. We have previously shown that neurons' responses to the onset of voicing are strongly dependent on their spectral sensitivity. This study examined the relation between neurons' temporal sensitivity, determined from responses to amplitude-modulated tones, and the same neurons' responses to the onset of voicing. Responses to VOT syllables and two types of modulated tones were obtained from low-frequency neurons in the inferior colliculus (IC) of the chinchilla. Both VOT and the modulation period varied from 10--70 ms in 10-ms steps. Neurons that respond selectively to modulated tones might be expected to respond strongly to the syllables whose VOTs match the preferred modulation periods. However, for most neurons the correlation between discharge rate to modulated tones and voicing onset was low. Some neurons exhibited moderate selectivity for certain modulation periods, but this selectivity was usually unrelated or even inversely related to the same neurons' selectivity for VOT syllables. Overall, responses to modulated tones did not account for the responses of IC neurons to the complex temporal cues associated with the onset of voicing. [Work supported by NIDCD.]