Neural responses to the onset of voicing are unrelated to other measures of temporal resolution

Voice onset time (VOT) is a temporal cue that can distinguish consonants su ch as /d/ from /t/. It has previously been shown that neurons' responses to the onset of voicing are strongly dependent on their static spectral sensi tivity. This study examined the relation between temporal resolution, deter mined from responses to sinusoidally amplitude-modulated (SAM) tones, and r esponses to syllables with different VOTs. Responses to syllables and SAM t ones were obtained from low-frequency neurons in the inferior colliculus (I C) of the chinchilla. VOT and modulation period varied from 10 to 70 ms in 10-ms steps, and discharge rates elicited by stimuli whose amplitude envelo pes were modulated over the same temporal interval were compared. Neurons t hat respond preferentially to syllables with particular VOTs might be expec ted to respond best to the SAM tones with comparable modulation periods. Ho wever, no consistent agreement between responses to VOT syllables and to SA M tones was obtained. These results confirm the previous suggestion that IC neurons' selectivity for VOT is determined by spectral rather than tempora l sensitivity. (C) 2000 Acoustical Society of America. [S0001-4966(00)01701 -X].