Individual Differences in Mothers' Spontaneous Infant-Directed Speech Predict Language Attainment in Children With Cochlear Implants

Abstract

Purpose Differences across language environments of prelingually deaf children who receive cochlear implants (CIs) may affect language acquisition; yet, whether mothers show individual differences in how they modify infant-directed (ID) compared with adult-directed (AD) speech has seldom been studied. This study assessed individual differences in how mothers realized speech modifications in ID register and whether these predicted differences in language outcomes for children with CIs. Method Participants were 36 dyads of mothers and their children aged 0;8–2;5 (years;months) at the time of CI implantation. Mothers' spontaneous speech was recorded in a lab setting in ID or AD conditions before ~15 months postimplantation. Mothers' speech samples were characterized for acoustic–phonetic and lexical properties established as canonical indices of ID speech to typically hearing infants, such as vowel space area differences, fundamental frequency variability, and speech rate. Children with CIs completed longitudinal administrations of one or more standardized language assessment instruments at variable intervals from 6 months to 9.5 years postimplantation. Standardized scores on assessments administered longitudinally were used to calculate linear regressions, which gave rise to predicted language scores for children at 2 years postimplantation and language growth over 2-year intervals. Results Mothers showed individual differences in how they modified speech in ID versus AD registers. Crucially, these individual differences significantly predicted differences in estimated language outcomes at 2 years postimplantation in children with CIs. Maternal speech variation in lexical quantity and vowel space area differences across ID and AD registers most frequently predicted estimates of language attainment in children with CIs, whereas prosodic differences played a minor role. Conclusion Results support that caregiver language behaviors play a substantial role in explaining variability in language attainment in children receiving CIs. Supplemental Material https://doi.org/10.23641/asha.12560147

Cochlear implant-related speech processing may diminish the advantage of exposure to infant-directed speech

“…This is expected to result in some caregivers’ exposing infants to relatively larger ranges of acoustic information, as compared to others, which would foster their infants’ speech processing and language acquisition by assisting infants in more robust recognition of their caregivers’ voices (Beauchemin et al, 2011; Kisilevsky et al, 2003), as well as better development of auditory cortical processing for language development (Webb et al, 2015). Similar to the recent findings by Dilley et al (2020), these results also suggest that IDS is not always readily distinguishable from ADS, due to the fact that caregivers vary in implementation of IDS. As such, these results confirm that conditions for recognition of IDS by infants is not always optimal (Piazza et al, 2017) and might differentially affect language outcomes for infants with CIs (Dilley et al, 2020).…”

“…Similar to the recent findings by Dilley et al (2020), these results also suggest that IDS is not always readily distinguishable from ADS, due to the fact that caregivers vary in implementation of IDS. As such, these results confirm that conditions for recognition of IDS by infants is not always optimal (Piazza et al, 2017) and might differentially affect language outcomes for infants with CIs (Dilley et al, 2020).…”

“…Prior studies on speech recognition in listeners with CIs have highlighted the importance of further examining patterns of individual differences, in addition to group differences (Dilley et al, 2020; Nagels et al, 2020; Peng et al, 2019; Spencer, 2004; Szagun & Schramm, 2016). Our investigation of patterns of individual differences across caregivers in acoustic distinctiveness between IDS and ADS and the simulated effect of limited spectral resolution in CI on these patterns highlighted multiple important observations.…”

Auditory feedback experience in phonetic development: Evidence from preschoolers with cochlear implants and their normal-hearing peers

“…However, that same degree of unintelligibility in a five-year-old child, who happens to have CIs, may appear exceptional to an adult interlocutor who does not anticipate that level of speech immaturity in an older child. This could render child-adult communication difficult, only exacerbating tendencies for children with hearing loss to be exposed to less speech from adult models in their environments (Ambrose et al, 2015;DesJardin and Eisenberg, 2007;Dilley et al, 2020;Holt et al, 2012;Kondaurova et al, 2020).…”

“…Among other consequences, this could mean that some phonemic contrasts are less distinguished in the children's input (Cristia and Seidl, 2014;Liu et al, 2003). Additionally, recent research Auditory feedback experience in phonetic development suggests that, compared to children with NH, children with hearing loss, and those fitted with CIs in particular, hear fewer conversational turns and fewer words from adult caregivers in their environments (Ambrose et al, 2015;DesJardin and Eisenberg, 2007;Dilley et al, 2020;Holt et al, 2012;Kondaurova et al, 2020). These patterns may continue post-implantation as families of children with severe hearing loss maintain early-established communicative patterns (Nittrouer et al, 2019).…”