Voice low tone to high tone ratio, nasalance, and nasality ratings in connected speech of native Mandarin speakers: A pilot study

Objective: Voice low tone to high tone ratio (VLHR) is defined as the power ratio of a voice spectrum with a specific cut-off frequency. Previous studies have shown that there are significant correlations between VLHR and nasalance and hypernasality ratings in vowels. The correlation was investigated in this study using connected speech material. Design: The Zoo Passage, the Rainbow Passage, the English Nasal Sentences, the Mandarin Nonnasal Sentences, and the Mandarin Nasal Sentences were used to acquire VLHRs, nasalance scores, and perceptual judgments of nasality. Each passage was recorded twice for averaging, and the cut-off frequencies from 200 Hz to 1200 Hz were used to survey for the presence of optimal correlations with VLHR. Participants: Ten native Mandarin speakers with an English learning history of over 8 years were enrolled. Main outcome measures: VLHRs, nasalance scores, and hypernasality ratings. Results: The correlations of VLHR with nasalance (rho = .76, p < .001, Spearman rank correlation) and nasality ratings (rho = .81, p < .001) were significant using a cut-off frequency of 300 Hz for the English passages. For the Mandarin Sentences, the optimal correlations of VLHR with nasalance (rho = .83, p < .001) and nasality ratings (rho = .79, p < .001) were identified using a cut-off frequency of 500-Hz. Conclusion: The significant correlations of VLHR with nasalance and perceptual ratings of nasality using connected speech show that these approaches have a potential value in terms of basic and clinical application.