Detecting hearing problems in young children can be hugely challenging, yet the earlier they are recognised, the greater chance the child has to get the necessary management and avoid language, learning and communication problems.

Even when babies are screened shortly after birth (using an otoacoustic emission test) and have a normal result, hearing difficulties may arise subsequently - and they may not always be obvious.

"The first indication of a problem usually has something to do with the young child not paying attention when spoken to, and it's typically the mother or main carer who notices this," says Adrian Dighe, chairman of British Paediatricians in Audiology. "Children under the age of three often have problems with speech delay.

"Older children may not realise you are speaking to them unless they are looking directly at your lips. They may have particular difficulty making out words when there is background noise."

In most cases, pharmacists will need to refer children with hearing problems to either a paediatric community audiology service or an ENT centre (via the GP). Pharmacists can, though, help parents to diagnose more minor problems, such as excess earwax.

Says Dr Dinghe: "If the child has any dark brown fluid in their ears, then it's probably wax. If it's yellow, then it's probably pus and the child should see their GP. Pharmacists can also help to advise with upper respiratory tract infections."

Glue ear

The most common type of conductive deafness in children - when sound cannot pass efficiently through the outer and middle ear to the cochlea and auditory nerve - is caused by glue ear (otitis media). The middle ear becomes clogged with mucus that fails to clear within three months, and this affects about one in five children at any time, according to the National Deaf Children's Society (NDCS).

Numerous conditions can influence glue ear, such as colds and flu, allergies and passive smoking. According to the NDCS, children with cleft lip and plate, or with genetic conditions such as Down's Syndrome, are more likely to get glue ear as they may have smaller eustachian tubes. But it can also develop unnoticed.

The resulting hearing loss from glue ear is usually moderate, but it can affect growth of language skills. "The peak time for getting glue ear is between the ages of two and five," says Dr Dighe.

A simple ear examination can diagnose glue ear and often a course of antibiotics is sufficient. If it fails to clear, then the fluid may be drained and grommets (tiny plastic tubes) can be inserted into the eardrum to allow air to circulate in the middle ear. Hearing aids are also sometimes used.

Sensori-neural deafness

It is not always possible to identify a cause of sensori-neural loss, which is permanent and results from problems in the inner ear or auditory nerve. It can be a result of an infection or medications taken during pregnancy (eg ototoxic drugs). When the cause is post-natal it may be due to measles, meningitis or mumps during early childhood. A head injury or loud noise exposure may also damage hearing.

This type of hearing loss is usually treated with a hearing aid or, if the loss is very profound, a cochlear implant. Says Dr Dighe: "This is usually accompanied by a rehabilitation process, whereby someone works with the child and the family to aid language development and perception of things in everyday life."

Auditory Processing Disorder

A new area of current research is auditory processing disorder (APD). Children with APD do not recognise subtle differences between sounds and words, and poor auditory processing is associated with poor verbal reasoning and reduced cochlear function.

"Listening problems are thought to underlie many learning problems in children, but at the moment we know very little about what contributes to those problems. This is why we're looking into the field and developing a battery of tests to diagnose APD in children," says Dave Moore, director of the MRC Institute of Hearing Research. According to Professor Moore, APD affects approximately 2 to 3 per cent of the population.

The institute is currently conducting a major study involving 1,600 children. Professor Moore says: "By the end of the year we should have clear recommendations on how to diagnose the condition and we'll then turn our attention to management strategies."

More information on hearing problems in children is available from the National Deaf Children's Society.