"My life has changed with a digital hearing aid, I sat in the conservatory yesterday and I heard the wind whistling for the first time in my life," says Margaret, who has suffered from hearing problems her whole life.
"Sitting in my lounge last night I heard the sound of a car engine in my street. My husband and daughter were conversing as they were going up the staircase and I heard their conversation. I can sit in the lounge and hear my daughter or husband engaged in conversation on the telephone in the kitchen. Although I cannot make out what they are saying - I can hear them. When I was in my local two days ago, one of my friends called my name and I looked round to see who was calling me. Think of the noise levels in a pub - but I heard my name being called."
Margaret is not the only person enjoying an enhanced quality of life due to digital hearing aids. Research has shown that digital hearing aids offer patients a 40 per cent improvement in hearing and quality of life.
This advance in hearing aid technology comes at a time when increasing numbers of people are suffering hearing problems. Approximately 8.7 million people in the UK are now suffering with significant hearing loss - that's about one in seven of the population and six million of these are over 60 years old.
Modern life is one of the contributing factors to this increase. Noise-induced hearing loss - as a result of regular exposure to dangerous levels of noise over a long period of time - is one example of this. The Royal National Institute for the Deaf (RNID) has started a campaign to warn people of the potential risks associated with exposure to loud noise in leisure time. Their "Don't lose the Music" campaign warns people "if you cannot talk to people two metres away without shouting because of background noise, the noise is a dangerous level for you to spend too much time in." It is not just hearing loss; tinnitus or becoming unusually sensitive to sound are also distracting and uncomfortable side effects of hearing damage.
The most common cause of hearing loss in developed countries is damage to the inner ear - the cochlea. A person with a damaged cochlea will experience a number of changes to how sound is perceived. They will lose sensitivity; finding it difficult to hear quiet sounds. There is also a problem of loudness recruitment where intense sounds appear as loud to the hearing-impaired person as they do to a normally hearing person. There is a loss of frequency selectivity - the ability to separate the different frequencies present in sound. This makes it harder to "hear out" the individual sounds in a mixture of sounds and means that it becomes difficult to hear someone talking if there is any background noise.
Traditional hearing aids partially compensate for loss of sensitivity by amplifying sounds. However they do not compensate for loudness recruitment, reduced frequency selectivity and perceived distortion.
However, digital hearing aids now incorporate a miniature computer to process sounds. They provide many possibilities for processing sounds in order to compensate more effectively for the hearing impairment. Unlike analogue hearing aids they can be adapted to suit the individual and adjusted to cope with different sound environments. Background noise, for example in a pub, can be suppressed resulting in conversations becoming significantly easier. The difference is similar to that between an analogue radio and a digital radio.
In April 2000 the government began making digital hearing aids available on the NHS for the first time. Currently a third of NHS audiology departments are providing them. In February this year Health Secretary Alan Milburn announced that an extra £94 million would be made available with the aim that digital hearing aids would be available in every hearing aid service throughout England by April 2005. There are 1.8 million hearing aid users who stand to benefit. Digital hearing aids cost £2000 if bought privately, but the NHS will pay £75 for each one.
The situation in England is therefore improving. The "postcode lottery" that exists at the moment shows signs of coming to an end. However RNID claims that awareness among doctors is poor - resulting in a large number of people not being offered the new devices. The situation in Scotland is far worse. There are 170,000 people in Scotland registered deaf or with a hearing aid who could benefit from the devices but at present less than two per cent have digital hearing aids. It must be hoped that as the technology improves and more money becomes available more people like Margaret will benefit from digital technology.
