Effects of the auditory environment on the fundamental-frequency dynamics of speech

The fundamental frequency (F0) is one of several voice features that talkers can alter in adverse communicative situations, e.g., when speaking in the presence of background noise or with hearing-impaired (HI) interlocutors, with the intent to produce 'clear speech' and increase intelligibility. Compared to 'conversational speech', clear speech has been shown to be characterized by a higher average F0 and a larger F0 dynamic range. However, these changes in F0 have commonly been measured in laboratory simulations with normal-hearing (NH) talkers speaking in the absence of an interlocutor. In contrast, the present study explored changes in F0 occurring in clear speech by analyzing the F0 statistics of naturalistic dialogues between NH interlocutors as well as between NH and HI ones, conducted in quiet and in background noise. It was found that (i) in the presence of background noise, both NH and HI talkers increased their average F0 and F0 dynamic range, and that (ii) when speaking with a HI interlocutor, NH talkers exhibited a higher average F0 and a larger F0 dynamic range than when speaking with a NH interlocutor. These results provide further evidence of how talkers modify their voice and speaking style depending on the auditory environment.