An acoustic–phonetic comparison of the clear speaking styles of Finnish–English late bilinguals

Abstract

Research on clear speech, an intelligibility-enhancing speaking style, has proposed that global clear speech modifications which make speech more perceptible in adverse conditions are language-independent, while the more fine-grained segmental clear speech modifications, which enhance the salience of phonological contrasts, are language-specific [Bradlow & Bent, 2002. The clear speech effect for non-native listeners. Journal of the Acoustical Society of America, 112, 272–284]. This study assessed the claim by contrasting the clear speech strategies used by twelve Finnish–English late bilinguals in their two languages, using spontaneous speech and sentence reading tasks. Their global clear speech modifications were also compared to those of native English speakers. Global measures included mean energy between 1 and 3kHz, f0 median and range, and speech rate, while segmental measures included VOT for initial stop consonants and spectral and temporal characteristics for two vowel contrasts. Findings generally support the hypothesis that global enhancements are language-independent: most of the global clear speech modifications were consistent across languages. However, segmental enhancements were not consistently language-dependent: the late bilinguals enhanced stop voicing contrasts according to the language being spoken, but vowels were modified similarly in the clear speaking style of both languages. The global clear speech strategies of late bilinguals were found to approximate those of native English speakers.