Summary of preliminary research findings
Timeliness of JCIH Benchmarks: Best practice recommendations are that newborns are screened for hearing loss by 1 month of age, have a diagnostic audiologic evaluation by 3 months of age, and are enrolled in appropriate early intervention services before 6 months of age. These are typically referred to as the 1-3-6 benchmarks. Of the children in the OCHL project who failed the newborn hearing screening, 64% had a confirmed diagnosis of hearing loss by 3 months, 66% were fit with hearing aids within one month after diagnosis and 75% were enrolled in early intervention by 6 months of age. Only 32%, however, met ALL of the benchmarks on time. Only mother's educational level was a significant predictor of the timeliness of diagnosis and follow-up. Reported barriers to timely follow-up included excessive wait times for appointments, variability in audiological test protocols, presence of otitis media, medical co-morbidities, multiple re-screenings, and misunderstandings on the part of families and physicians about subjective auditory response behaviors of children with mild and moderate hearing loss. (See Holte, et al, in press.)
Audibility of Hearing Aid Fittings: Our current findings indicate that audibility (SII) contributes to vocabulary and speech production outcomes. Audibility less than .65 has been associated with reduced speech and language outcomes (Stiles et al, 2012). Although most children in the study are adequately fit (SII better than .25), nearly half are not optimally fit to prescribed amplification targets. This means that many children are not receiving the appropriate amount of amplification that is prescribed for their hearing loss. Hearing aid fittings with limited audibility have implications for typical development of speech and language. Age and degree of hearing loss were not significant predictors of deviations from prescriptive target or limited audibility. Most of the audiologists who fit the hearing aids on the children in the study reported using best practices in a survey. A manuscript related to these findings is currently in review.
Consistency of Hearing Aid Use: Our goal is for children to wear their hearing aids full time when they are awake. Children in the OCHL study vary in the amount that they wear their hearing aids, especially the youngest children (under two years). Three variables – severity of hearing loss, chronological age, and maternal education level – were significantly related to the amount of time children wore their hearing aids. Parental ratings regarding consistency of hearing aid use across different listening environments confirmed the findings of the regression analysis, as younger children and children with milder hearing losses wore their hearing aids less consistently than older children and children with moderate-to-severe hearing loss in a variety of contexts. (See Walker, et al.,2012.)
Accuracy of Parent Reports of Hearing Aid Use: When parent reporting of children's hearing aid use time was compared to objective data logging measures, most parents overestimated the amount of time their child wore his or her hearing aids (on average, by 2.5 hours). There was a significant positive correlation between parents' subjective estimates and objective measures using data logging ( r = .76, p < .0001), indicating that parents were overestimating hearing aid use time by about the same degree. Therefore, clinicians may rely on parental self-report of hearing aid use time as a general estimate of how much the child wears amplification. (See Walker, et al.,2012.)
Risk and Resilience in Speech and Language: Children with mild to severe hearing loss, on average, are performing well in terms of communication outcomes. Although there is considerable variability in scores at each age, the majority of children fall within the average range on several standardized measures of speech and language. However, selected areas of development show greater risk than others, particularly those related to language structure (phonology/grammar). This is not surprising, given that these aspects of language development are driven by details of the input, which may be inconsistently accessed by hard-of-hearing children. These results suggest that early identification alone is not enough to bring about “typical” outcomes. A profile of “risk and resilience” seems to characterize this group of children, and it is imperative to determine if these areas of risk/delay have later developmental consequences. Delays in structural aspects of language may become problematic in academic settings with advanced linguistic requirements. Longitudinal aspects of our work place us in a unique position to address sources of variability in outcomes and consequences of early delays for later academic and socials achievements. A manuscript related to selected language findings will be published soon (Koehlinger, et al., in revision ).
Emergent and Early Literacy Skills: Children who are hard of hearing also demonstrate a unique risk-resilience pattern in emergent literacy skills: print knowledge is a relative strength, while preschool phonological awareness is often depressed. Reading comprehension scores are better than predicted based on the children's phonological awareness abilities. This suggests the possibility that children who are hard of hearing have unique developmental profiles, possibly reflective of inconsistent access to structural details of the input when hearing loss is present.
Social-Cognitive Development: Another identified area of risk is social cognition, or Theory of Mind development. Children with normal hearing passed standard false belief tasks at a significantly higher rate than children with hearing loss (84% vs. 34% respectively, p = .001). Previous studies have not examined these abilities in a homogenous group of hard-of-hearing children. It is possible that difficulty accessing multi-talker conversations, particularly in noisy settings, contributes to these social-cognitive delays. It may be that challenges with advanced syntax influence performance on theory of mind tasks. The findings and related hypotheses motivate the need to examine higher-order social-cognitive skills and their impact on functional social skills. Furthermore, studies of typically-developing children document the direct impact of social functioning on academic performance. This speaks to the need to examine functional social and academic outcomes in children with hearing loss from the perspective of life competence. Competence is a socially-defined construct, known to contribute to Quality of Life.
Language and Auditory Environments: The OCHL team was awarded a supplemental grant to examine the linguistic and auditory environments of a subgroup of children participating in the OCHL study. Using new wearable technologies (LENA or Language ENvironment Analysis), it is possible to collect full-days recordings of family-child interaction in natural environments. Our team has collected consecutive monthly recordings from about 50 children. In a recent study, we collected all-day recordings of the auditory environments of 32 HH 2 year olds, and examined them for number of adult words (AWC), conversational turns (CTC), and television duration. Children's language abilities were assessed at 2 years, and, for a subset, again at 3 years. AWC and CTC were positively correlated with receptive and expressive language, and TV was negatively correlated with receptive language. CTC and TV explained unique variance in receptive language scores. Only CTC was related to 3 year old language. These findings suggest that high rates of linguistic input, especially within conversational interactions, facilitates the language development of HH toddlers. In contrast, television exposure may have a detrimental effect on language outcomes. A manuscript related to this project is in preparation; see Van Dam, Ambrose and Moeller (2012) for additional information on this subproject.
Supported by NIDCD R01 DC009560