Are the consequences of neonatal hearing loss serious enough that we need to be concerned about them in the first place? Fortunately, there is a wealth of data on this question, and only three very brief examples will be given related to children with severe profound bilateral losses, children with mild bilateral and unilateral losses, and children with fluctuating conductive losses (slide #46).
Slide #47 shows data from an annual survey done each year by Gallaudet University showing that children with severe profound bilateral losses suffer from substantial deficits in reading comprehension. When these children are 8 years of age, they are already almost 1-1/2 years behind their peers. That gap continues to widen over time, with the average deaf child or youth never exceeding a grade equivalent of 3 years, in spite of the fact that most of them are enrolled in educational programs specifically designed for deaf students. Of course, most of these children did not have the benefit of very early identification.
Although virtually everyone agrees that severe profound bilateral hearing loss has substantial negative consequences for all aspects of academic performance, the consequences of mild bilateral or unilateral hearing loss are less well known. There are, however, a number of studies demonstrating that even mild or unilateral sensorineural hearing loss has substantial negative consequences. Slide #48 summarizes information about five different students in which a sample of children with unilateral hearing loss were compared to similar children with normal hearing, and measures were taken about their performance in math, language, and social functioning. As shown in slide #49, children with unilateral hearing loss lagged substantially behind their peers regardless of the measure used, whether math, language, or social functioning. Even though the sample sizes are quite small in each of the studies, matching was generally done quite well and the results are very consistent. For a 10-year-old child, these results translate into a deficit of approximately 1-1/2 years in math or reading achievement.
Even mild fluctuating conductive hearing loss can have a substantial effect over time. Although virtually all newborn hearing screening programs focus only on identifying children with permanent congenital hearing loss, some children with fluctuating conductive losses are often identified. The reason for presenting this information is to emphasize the point that even mild fluctuating hearing losses have an important negative effect on developmental outcomes. How much more important it is then to identify children with permanent hearing losses.
The data in slide #50 come from the Greater Boston Otitis Media Study Group, where 194 children were followed prospectively for 7 years. Each time the child visited his or her primary- care physician, data were collected about episodes of otitis media (there were an average of 7 visits per year during the birth to 3-year-old period). Data were also collected periodically on a wide variety of measures related to intellectual ability, cognitive functioning, and language competency by trained diagnosticians who were uninformed about the purposes of the study. Results at 7 years of age for two groups of children are reported here: those with less than 30 days of otitis media over the 3-year period compared to those with 130 or more days of otitis media over the same period. After statistically adjusting the results for a variety of demographic and socio-economic status variables, children with fewer episodes of otitis media did substantially better than their peers on all measures. The difference averaged about one-half standard deviation, which is equivalent to more than a year's worth of development in reading or math achievement.
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