Most children have their hearing checked by health visitors at around eight months. But studies show that this test fails to pick up most permanent hearing problems. Another test, performed within days of birth, can detect virtually all permanent hearing loss and allows earlier help to be given.
Childhood hearing problems
About one child in every 1000 (840 children a year) is born with permanent hearing loss, mainly due to damage to the cochlea or auditory nerve and occasionally to defects in the outer or middle ear. About 160 more children acquire permanent hearing loss each year, mostly through meningitis. In addition, most children suffer spells of "glue ear", when fluid builds up behind the eardrum, causing temporary hearing problems, but generally this clears up on its own.
Hearing tests
Childhood hearing tests are meant to detect permanent hearing problems so they can be treated early. The commonest check - used in 98% of health districts - is the infant distraction test, carried out by health visitors on babies between six and nine months. It tests the ability to turn towards noises, but its detection rate is poor. The test often fails infants with normal hearing, causing unnecessary anxiety in parents, yet profoundly deaf children may pass easily. However, the transient evoked otoacoustic emissions (TEOAE) test, which can be carried out in hospital within days of birth, is almost foolproof. It involves inserting a small probe in the baby's ear to detect signals that the ear is working. Comparative trials reveal that the health visitor test detects only one in 10 permanent hearing problems, while the TEOAE test picks up about 98%. The TEOAE costs nearly half that of the health visitors' check.
Earlier treatment
There is no cure for these hearing problems, but hearing aids, cochlear implants and early educational support, such as teaching sign language, can all help the child communicate better and perform well at school. Several studies show that starting this help before six months is better for language development. Only a handful of health districts now offer universal TEOAE screening, but there are plans to set up 20 more pilot sites.
• What works? is based on reviews of the most up-to-date and reliable evidence available. It is written in collaboration with the NHS Centre for Reviews and Dissemination at York university (01904-433634) and verified by experts.
