Formant dynamics of bilingual identical twins

This study investigates speech similarities in bilingual identical twins using formant dynamics. Previous studies show both similarities and differences in static features between twin speakers, but it is unclear if differences also exist in dynamic features, given that identical twins have the same vocal tract anatomy which allows them to reach the same phonetic targets with the same articulatory strategies. Moreover, previous studies show that bilingual speakers exhibit different speech patterns in their two languages. The degree of variability between the two languages of identical twins is also unknown. Eight pairs of Shanghainese-Mandarin bilingual identical twins were recorded producing the common diphthong /ua/ in both languages in two recording sessions. Frequencies of the first four formants were measured at each +10% step. The results show clear differences in formant dynamics between identical twins, and the differences were large enough to discriminate them using Discriminant Analysis. The twin speakers were more similar in their dominant language than in their non-dominant language. Twins raised separately were as similar as twins growing up together. The results suggest that individual choices play an important role in shaping the speech of identical twins.