Understanding speech in noisy environments is important to daily communication and functioning. Recent evidence suggests that speech intelligibility in noise is adversely affected by degrading the fundamental frequency (F0) pitch contour. However, the relationship between cortical speech tracking and the impact of F0 pitch contour on speech intelligibility remains unclear. This study investigates how the F0 pitch contour modulates neural tracking of speech in noisy backgrounds. The amount of F0-pitch contour information was manipulated by flattening either at the tone-level or across all levels (i.e., monotone) in speech sentences. A cohort of 30 normal-hearing adults listened to original, flat-tone, and flat-all Mandarin Chinese sentences masked under three signal-to-noise ratios (SNRs: 0, ‒9, ‒12 dB) while their electroencephalogram (EEG) was recorded. Speech comprehension accuracy and perceptual musical skills related to speech-in-noise perception was also examined. Neural envelope tracking was indexed by the temporal response function between amplitude envelope of speech and EEG response. Results showed that both F0 contour and signal-to-noise level modulated the amplitude of an early neural component in the delta and theta frequency bands. Specifically, decreasing signal-to-noise level results in reduced peak amplitude around 100 ms of the temporal response function in the theta frequency band. Moreover, flattening the F0 contour decreases the amplitude peaking around 100 ms of the temporal response function in the delta frequency band. These findings indicate that neural speech tracking is highly responsive to variations in F0-pitch contour, highlighting the crucial role of fundamental frequency in enhancing speech perception, especially in noisy environments.

Authors:
I-Hui Hsieh, National Central University, Taiwan
Yu-Jyun Guo, National Central University, Taiwan

About the Presenter(s)
Professor I-Hui Hsieh is a University Associate Professor/Senior Lecturer at National Central University in Taiwan

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