Differences in voice quality measures among monolingual and bilingual speakers

While extensive research exists on the variations in voice quality measures among different languages, the impact of bilingualism on voice characteristics has been relatively understudied in the literature. This study explores the divergences among monolingual and bilingual speakers in various voice quality measures. The participants were adult Greek monolingual and adult Albanian-Greek sequential bilingual speakers, who permanently lived in Greece. All speakers participated in a controlled sentence production task which targeted the Greek vowels. Acoustic measures such as fundamental frequency (F0), first four formants (F1-F4), duration, jitter, shimmer, harmonics-to-noise ratio (HNR), and intensity we elicited from the speech samples. Differences were identified in the majority of voice parameters for certain vowels, implying that the vocal characteristics of bilinguals may demonstrate distinct adaptations compared to those of monolinguals in certain instances. Jitter displayed the most pronounced differences across vowels, followed by F2, shimmer, and HNR, with F3, F4, and duration showing relatively fewer distinctions. It is established that sequential bilingual speakers may exhibit variations from monolingual speakers across multiple acoustic parameters and that voice quality parameters can also manifest as sound-specific. These findings hold practical significance for the evaluation and therapeutic interventions tailored to bilingual individuals within clinical settings.