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Discussions about the use of popular technology that uses earbuds or other earpieces by children-and its potential affect on their hearing-are closely related to studies that have been conducted for the last 20 years at the Vanderbilt Bill Wilkerson Center. There, investigators have focused much of their effort on children with minimal hearing loss. Minimal hearing loss typically refers to unilateral hearing loss (in only one ear), slight bilateral hearing loss (in both ears), and high frequency hearing loss (for very high-pitched sounds only).
As we have come to learn, the term "minimal" tends to misrepresent the impact such hearing deficits can have on the psychosocial and educational progress of young children. Our interest in this population began in the early 1980's when we noted that a considerable number of children with unilateral hearing loss were having significant academic difficulties. This was quite a surprise because professional opinion at that time suggested that such children would have no difficulty as long as they were seated preferentially in the classroom. However, our research revealed that children with unilateral hearing loss were ten times more likely to suffer academic difficulties than their normal hearing peers. In fact, one third of the children we examined with unilateral hearing loss experienced grade repetition or required resource assistance in school. In addition, if the hearing loss was in the right ear, the children were even more likely to have academic difficulty than if the loss was in the left ear.
These findings about children with unilateral hearing loss spurred some Bill Wilkerson Center investigators to take a closer look at children with all types of minimal hearing loss. Investigators went out into Tennessee middle schools and sampled approximately 1,200 children in the third, sixth, and ninth grades. Minimal hearing loss was exhibited by 5.4% of the study sample. Prevalence of all types of hearing impairment was 11.3%. Scores were obtained on the Comprehensive Test of Basic Skills (CTBS), the Revised Behavior Problem Checklist, and the COOP Adolescent Chart Method, a screening tool for functional status. Furthermore, data on grade retention were obtained from school records and compared to school district normative data. Third grade children with minimal hearing loss exhibited significantly lower scores than their normally-hearing peers on subtests of the CTBS. Interestingly, 37% of all children with minimal hearing loss failed at least one grade, compared to the 3% district norm failure rate. These children also exhibited more dysfunction than children with normal hearing as documented on the COOP on social and emotional domains of stress, self-esteem, behavior, energy, and support.
In an attempt to follow up on these findings, a Ph.D. student, Candace Bourland Hicks, and I utilized a dual-task paradigm to study listening effort in children with mild hearing loss (listening effort refers to the attentional requirements necessary to understand speech). Study subjects were asked to perform a primary task (repeating words presented in the presence of background noise) and a secondary task (pushing a button whenever they saw a probe light turn on). The assumption was that performance on the primary task used mental capacity, and performance on the secondary task, spare mental capacity. Decreases in performance on the secondary task would reflect an increase in the effort required for the primary task. Although this test technique has been used to measure effort in adults, to our knowledge it has not been used with children. Study results indicated that children with hearing loss expended more effort listening than children with normal hearing in easy and difficult listening conditions. Interestingly, all listening conditions incorporated better acoustic conditions than those found in typical classroom settings. Therefore, children with hearing loss are at risk for expending greater effort listening in typical classroom environments than their normal hearing peers. Assuming that there is a limit to one's effort capacity, it is possible that children may miss important things in the classroom if they are already expending a significant amount of effort on other tasks.
The implications of these findings require more investigation. However, these results suggest that the increased expenditure of effort documented in this study may be responsible, at least in part, for the academic difficulties experienced by these children. Certainly, it is reasonable to speculate that classwork may suffer if a child with hearing loss is expending extra mental or cognitive effort simultaneously to listen to the teacher, take notes, and process what is being heard.
Return to Anne Marie Tharpe's Biography
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