Interlocutor accommodation of gradually altered nasal signal levels in a model speaker

Background: Phonetic accommodation is observed when interacting speakers gradually converge (or diverge) on phonetic features over the course of a conversation. The present experiment investigated whether gradual changes in the nasal signal levels of a pre-recorded model speaker would lead to accommodation in the nasalance scores of the interlocutor in a speech-shadowing experiment. Methods: Twenty female speakers in two groups repeated sentences after a pre-recorded model speaker whose nasal signal level was gradually increased or decreased over the course of the experiment. Outcome measures were the mean nasalance scores at the initial baseline, maximum nasal signal level, minimum nasal signal level and final baseline conditions. The order of presentation of the maximum and minimum nasal signal levels was varied between the two groups. Results: The results showed a significant effect of condition in F(3) = 2.86, p = 0.045. Both groups of participants demonstrated lower nasalance scores in response to increased nasal signal levels in the model (phonetic divergence). The group that was first presented with the maximum nasal signal levels demonstrated lower nasalance scores for the minimum nasal signal level condition (phonetic convergence). Conclusion: Speakers showed a consistent divergent reaction to a more nasal-sounding model speaker, but their response to a less nasal-sounding model may depend on the order of presentation of the manipulations. More research is needed to investigate the effects of increased versus decreased nasality in the speech of an interlocutor.