Infant‐directed speech does not always involve exaggerated vowel distinctions: Evidence from Danish

Abstract

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.

Mothers’ and fathers’ infant-directed speech have similar acoustic properties, but these are not associated with direct or indirect measures of word comprehension in 8-month-old infants

“…A growing body of research, using advanced acoustic analyses, provides evidence against the hypothesis of enhanced clarity of IDS, implying that the traditionally reported vowel space area may be a too crude proxy for the 'clear speech' claim. Vowel categories in IDS appear to be less distinctive, as compared to ADS: they are separated by smaller acoustic distances (Cox et al, 2023;Cristia & Seidl, 2014); and spectral differences between them are reduced (Martin et al, 2015). In addition, vowels in IDS appear to be more variable, as revealed by larger within-category variability (Cristia & Seidl, 2014;Englund, 2018;McMurray et al, 2013;Miyazawa et al, 2017;Rosslund et al, 2022) and larger change in the spectral dynamics over the vowel duration (Miyazawa et al, 2017).…”

“…-Higher pitch in IDS (Cox et al, 2022) -Wider pitch range in IDS (Cox et al, 2022) -More prominent pitch change in IDS (Benders et al, 2021) -Slower articulation rate in IDS (Cox et al, 2022) -Longer vowel duration in IDS (Cox et al, 2022) -Increased vowel space expansion in IDS (Cox et al, 2022) -More variable vowel categories in IDS (Cox et al, 2023;Rosslund et al, 2022) -Less distinct vowel categories in IDS (Cox et al, 2023;Rosslund et al, 2022) Based on the above-reviewed literature showing that, overall, fathers also adapt their IDS, we expected that both mothers' and fathers' IDS in our sample would follow the above patterns, although with some nuances. First, given that, when infants are 8-months old, mothers would likely have spent more accumulated time with their child as compared to fathers (Norwegian Labour and Welfare Administration, 2022), we expected mothers to show larger differences between the registers for six of eight measures, as they would have more time to potentially fine-tune the speech signal to infants' needs (Han et al, 2020;Leung et al, 2021).…”

“…To acquire this measure, we used version 3 of the Praat script by de Jong and Wempe (2009), which automatically detects syllables, based on peaks, and preceding and subsequent dips, in intensity. A similar approach to IDS data was used by Cox et al (2023).…”

Language‐Specific Constraints on Conversation: Evidence from Danish and Norwegian

“…The dynamics of mutual understanding are an integral part of how we understand human cognition in context (e.g., Dale, Fusaroli, Duran, & Richardson, 2013;Fusaroli, Demuru, & Borghi, 2012;Schilbach et al, 2013), and are becoming crucial components in the development of human-computer interfaces (Loth, Jettka, Giuliani, & De Ruiter, 2015;Sugiyama, Meguro, Yoshikawa, & Yamato, 2018), and clinical assessments of social functioning (Dwyer, David, McCarthy, McKenna, & Peters, 2019;Hopkins, Yuill, & Keller, 2016;Schilbach et al, 2013). However, the extent to which they vary and adapt to different contextual constraints (e.g., a casual chat vs. reaching a joint decision at work vs. helping a child in developing their language) is only now starting to be systematically investigated (Colman & Healey, 2011;Cox et al, 2022aCox et al, , 2022bDideriksen, Christiansen, Tylén, Dingemanse, & Fusaroli, 2023;Healey, Purver, & Howes, 2014). Similarly, while it is acknowledged that cross-linguistic and cross-cultural variations play a crucial role in human behavior and cognition (Christiansen, Contreras Kallens, & Trecca, 2022;Cox et al, 2022aCox et al, , 2022bHenrich, Heine, & Norenzayan, 2010;Trecca, Tylén, Højen, & Christiansen, 2021), very little is known about how conversational dynamics systematically vary and adapt to diverse languages and cultures.…”

“…However, the extent to which they vary and adapt to different contextual constraints (e.g., a casual chat vs. reaching a joint decision at work vs. helping a child in developing their language) is only now starting to be systematically investigated (Colman & Healey, 2011;Cox et al, 2022aCox et al, , 2022bDideriksen, Christiansen, Tylén, Dingemanse, & Fusaroli, 2023;Healey, Purver, & Howes, 2014). Similarly, while it is acknowledged that cross-linguistic and cross-cultural variations play a crucial role in human behavior and cognition (Christiansen, Contreras Kallens, & Trecca, 2022;Cox et al, 2022aCox et al, , 2022bHenrich, Heine, & Norenzayan, 2010;Trecca, Tylén, Højen, & Christiansen, 2021), very little is known about how conversational dynamics systematically vary and adapt to diverse languages and cultures.…”