A potential approach for reducing hearing difficulty by improving perception of intensity changes in speech

Abstract

Many listeners report hearing difficulty, especially for speech in noisy environments, despite having normal audiometric thresholds. Recent work suggests that such cases may be caused by disruptions in coding of suprathreshold sounds at early stages of auditory processing. Specifically, differences in the function of auditory nerve fibers with lower spontaneous firing rates could disrupt coding of intensity changes for sounds in the typical range used for speech communication. In turn, this could affect perception of acoustic cues in speech that are dependent on intensity changes over time, such as voice onset time (VOT). The current study investigated a speech sound manipulation designed to counteract the effects of such disruptions by making intensity differences in the signal more pronounced. Listeners heard speech sounds varying along two acoustic dimensions that provide information about word-initial voicing, VOT and f0 onset, and categorized sounds as either voiced or voiceless. Results showed that the intensity manipulation reduced listeners' use of f0 for voicing categorization and also affected their use of VOT. This suggests that intensity manipulations can make acoustic cues like VOT more salient, providing a potential treatment approach for listeners who have difficulty coding intensity differences in speech.