Early Hearing Loss Detection Improves Language Skills

The early detection of hearing impairment in babies significantly improves the language ability of affected children in later childhood, a new study led by Dr Colin Kennedy of the University of Southampton has revealed.

The study of 120 children with permanent hearing impairment in the south of England shows that their language skills were stronger at eight years of age if their hearing difficulties had been confirmed before they were nine months old than if they had been confirmed later. However, the study also showed that a hearing impaired child's speech is not greatly benefited by early detection.

One in 750 children in the UK is born with moderate, severe or profound bilateral permanent hearing impairment, which is present at birth in more than 80 per cent of affected children. Such impairments are associated with impeded language acquisition, learning and speech development.

Previous work in Southampton, also led by Dr Kennedy, established that screening of all newborn babies for this condition with a simple bedside screening was effective in increasing the proportion of babies with permanent hearing impairment who were referred before the age of six months for audiological evaluation and treatment from 31 per cent to 74 per cent.

Following the publication of this finding in The Lancet, a universal newborn screening service was introduced across the UK and, as of this year, is available in every UK district. The justification for this screening is that early detection would be followed by benefits to the child's acquisition of language but hitherto the evidence to support this assumption has been weak and inconclusive.

The same team at the University of Southampton, with funding from the Wellcome Trust, has now assessed expressive and receptive language skills of primary school age children, including those that were involved in the previous study on universal newborn screening.

'Receptive language' is the ability to understand communication through gestures, facial expressions and words, while 'expressive language' is the ability to express needs with the use of gestures, vocalisation, facial expressions and words. Other characteristics of the hearing impaired child and family, including the severity of the hearing impairment, the non-verbal ability of the child and the education of the mother, were also taken into account.

Those children in the study whose hearing problems were identified by the time they were nine months of age had significantly better receptive and expressive language skills than those whose problems were confirmed later. Children who were screened as newborns had higher scores for receptive language ability than those who were not screened. However, in contrast to the higher language scores observed among children whose hearing impairment was confirmed early, measures of speech did not differ significantly between groups.

Dr Kennedy, Reader in Child Health at Southampton, said: 'Our study extends findings from previous studies of the relationship between early identification of hearing impairment and later outcomes. Until now it has not been certain whether universal screening of newborn babies for hearing impairment and the confirmation of hearing impairment by nine months of age has any effect on the child's subsequent verbal abilities.

'Screening and early confirmation of permanent childhood hearing impairment clearly do have clinically important benefits to the language abilities of children at primary school age. However a longer follow-up with these children is needed to establish whether at secondary school age they continue to show superior language skills and have higher academic achievement,' he continued.

This new study therefore vindicates the decision to introduce universal newborn screening in the UK. It also provides indirect support for the idea that there is a 'sensitive period' during infancy when exposure to the sounds of language is particularly important for the brain development that underlies the subsequent acquisition of language.

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