Can you hear me? acoustic modifications in speech directed to foreigners and hearing-impaired people

People modify their voice to accommodate the communicative needs of their audience. Previously, speech recipient groups with communicative needs such as foreigners and infants have been investigated, however, there is a lack of research into speech directed to hearing-impaired people. The aim of our study was to investigate prosodic modifications in speech directed to hearing-impaired people and foreigners, and the benefit of such modifications to the listener. Ten speakers were recorded in natural interactions with a hearing-impaired person (HIDS), a foreigner (FDS) and a native speaker (ADS). The resulting speech was acoustically analysed for duration, vowel hyperarticulation, intensity, mean fundamental frequency (F0) and F0 range. There was no significant difference in duration, F0 range or intensity between the conditions. HIDS and FDS displayed significantly higher mean F0 and hyperarticulation than ADS. The speech was also rated by twenty speakers for positive vocal affect and intelligibility. HIDS was perceived to be more positive and intelligible than both FDS and ADS, with no difference between the latter two groups. These results show that people modify the acoustic properties of their voice in interactions with foreigners and hearing-impaired people, but that the benefits of these modification are more noticeable in HIDS than FDS.