Objectives: This study aims to examine whether language could influence speakers’ vocal characteristics. By investigating voice quality associated with Mandarin Chinese and English spoken by proficient Mandarin-English bilingual speakers, potential influence of language on voice quality can be revealed. Findings provide evidence for the cross-linguistic standardization of voice assessment tools.

Methods / Design: Thirty adult Mandarin-English bilingual speakers were recruited. Each participant read standardized Mandarin and English passages, and the acoustic signals of their productions were recorded and digitized (44.1 kHz sampling rate), and all samples will undergo loudness normalization to control for intensity differences. Acoustic parameters, including fundamental frequency (F0), jitter, shimmer, cepstral peak prominence (CPP), and harmonics-to-noise ratio (HNR), were extracted using Praat. Statistical analyses were carried out to compare parameters between the two languages.

Results: Preliminary results showed greater jitter and shimmer, lower CPP, and a wider F0 range values when speaking English compared to Mandarin, reflecting greater pitch variability and slightly reduced overall voice quality in English.

Conclusions: Language appears to be a covariate for the voice quality. The present study suggests that even within the same individual, switching between languages may lead to significant changes in acoustic characteristics and perceptual voice quality. These findings indicate the need for caution when interpreting and comparing voice assessment results across speakers of different linguistic backgrounds. Future research should further explore the interactions among language, phonatory mechanisms, and perceptual evaluation.