Temporally jittered speech produces performance intensity, phonetically balanced rollover in young normal-hearing listeners

This study investigates whether temporally jittered stimuli will produce performance-intensity, phonetically balanced (PI-PB) rollover in young adults with normal hearing. Although not yet explicitly stated in the literature, there is clinical and theoretical evidence to suggest that PI-PB rollover, such as that found in cases of acoustic neuroma, is caused by neural dyssynchrony in the auditory system. Sixteen participants were tested with intact and temporally jittered word lists in quiet at 40, 55, 65, and uncomfortable listening level -5 dB HL. The results show significant rollover in the jittered but not the intact conditions. The results are consistent with the existing evidence that suggests that neural PI-PB rollover is caused by decreased neural synchrony and support the claim that temporal jitter simulates neural dyssynchrony. Furthermore, these results are consistent with the hypothesis that synchrony coding plays an important role in the perception of high-level speech.