Cortical Pitch Response Components Correlate with the Pitch Salience of Resolved and Unresolved components of Mandarin Tones

Cortical pitch responses (CPRs) are generated at the initiation of pitch-bearing sounds. CPR components have been shown to reflect the pitch salience of iterated rippled noise with different temporal periodicity. However, it is unclear whether features of the CPR correlate with the pitch salience of resolved and unresolved harmonics of speech when the temporal periodicity is identical, and whether CPRs could be a neural index for auditory cortical pitch processing. In this study, CPRs were recorded to two speech sounds: a set including only resolved harmonics and a set including only unresolved harmonics. Speech-shaped noise preceding and following the speech was used to temporally discriminate the neural activity coding the onset of acoustic energy from the onset of time-varying pitch. Analysis of CPR peak latency and peak amplitude (Na) showed that the peak latency to speech sounds with only resolved harmonics was significantly shorter than for sounds with unresolved harmonics (p = 0.01), and that peak amplitude to sounds with only resolved harmonics was significantly higher than for sounds with unresolved harmonics (p < 0.001). Further, the CPR peak phase locking value in response to sounds with only resolved harmonics was significantly higher than to sounds with only unresolved harmonics (p < 0.001). Our findings suggest that the CPR changes with pitch salience and that CPR is a potentially useful indicator of auditory cortical pitch processing.