Infant-Directed Speech Does Not Always Involve Exaggerated Vowel Distinctions:Evidence From Danish

This study compared the acoustic properties of 26 (100% female, 100% monolingual) Danish caregivers' spontaneous speech addressed to their 11‐ to 24‐month‐old infants (infant‐directed speech, IDS) and an adult experimenter (adult‐directed speech, ADS). The data were collected between 2016 and 2018 in Aarhus, Denmark. Prosodic properties of Danish IDS conformed to cross‐linguistic patterns, with a higher pitch, greater pitch variability, and slower articulation rate than ADS. However, an acoustic analysis of vocalic properties revealed that Danish IDS had a reduced or similar vowel space, higher within‐vowel variability, raised formants, and lower degree of vowel discriminability compared to ADS. None of the measures, except articulation rate, showed age‐related differences. These results push for future research to conduct theory‐driven comparisons across languages with distinct phonological systems.