Audiometric screening services

What are the effects of Noise Induced Hearing Loss (NIHL)?

The effect from impulse sound can be instantaneous and can result in an immediate hearing loss that may be permanent. The structures of the inner ear may be severely damaged. This kind of hearing loss may be accompanied by tinnitus, an experience of sound like ringing, buzzing or roaring in the ears or head, which may subside over time. Hearing loss and tinnitus may be experienced in one or both ears, and tinnitus may continue or intermittently throughout a lifetime.

The damage that occurs slowly over years of continuous exposure to loud noise is accompanied by various changes in the structure of the hair cells. It also results in hearing loss and tinnitus. Exposure to impulse and continuous noise may cause only a temporary hearing loss. If the hearing recovers, the temporary hearing loss is called a temporary threshold shift. The temporary threshold shift largely disappears within 16 hours after exposure to loud noise. Both forms of NIHL can be prevented by the regular use of hearing protectors such as ear plugs or ear muffs.

What are the symptoms of noise-induced hearing loss?

One reason people fail to notice the danger of noise is that excess exposure to noise causes few symptoms. Hearing loss is rarely painful. The symptoms are usually vague feelings of pressure or fullness in the ears, speech that seems to be muffled or far away, and a ringing sound in the ears that you notice when you are in quiet places. These symptoms may go away minutes, hours or days after the exposure to noise ends.

People assume that if the symptoms go away, their ears have "bounced back" to normal. This is not really true. Even if there are no more symptoms, some of the sensory cells in the inner ear may have been destroyed by the noise. Your hearing returns to normal if enough healthy sensory cells are left in your inner ear. But you will develop a lasting hearing loss if the noise exposure is repeated and more sensory cells are destroyed. The first sign of a noise-induced hearing loss is not hearing high-pitched sounds, like the singing of birds, or not understanding the speech of women and small children. If the damage goes on, hearing declines further, and lower pitched sounds, including men's voices, become hard to understand.

How can you decide which noises are too loud?

The following signs should be an indication that the noise around you is too loud:

If you have to shout to be heard above the noise.

If you can't understand someone who is speaking to you from less than 2 feet away. If a person standing near you can hear sounds from your stereo headset while it is on your head.

How can I prevent noise-induced hearing loss?

Reduce your exposure to noise. This step is especially important for people who work in noisy places and who go to and from work in noisy city traffic. You can reduce your exposure to noise by choosing quiet leisure activities rather than noisy ones.

Develop the habit of wearing earplugs when you know you will be exposed to noise for a long time. Earplugs, which can reduce noise levels by 25 dB, can mean the difference between a dangerous and a safe level of noise. You should always wear ear-plugs when engaged in noisy hobbies and activities such shooting, motor sports or when using power tools, lawn mowers or leaf blowers.

Don't use several noisy machines at the same time. Try to keep television sets, stereos and headsets low in volume. Loudness is a habit that can be broken.

Don't try to drown out unwanted noise with other sounds. For example, don't turn up the volume on your car radio or headset to drown out traffic noise or turn up the television volume while vacuuming.

Have your hearing checked. Persons at risk for hearing loss should have their hearing tested every year. You are at risk if you are regularly exposed to loud noise at work or play.

Measuring hearing loss and deafness

Hearing loss and deafness is usually measured by finding the quietest sounds someone can hear using tones with different frequencies - which are heard as different pitches. The person being tested is asked to respond - usually by pressing a button - when they can hear a tone and the level of the tone is adjusted until they can just hear it. This level is called the threshold.

People with mild deafness have some difficulty following speech, mainly in noisy situations. The quietest sounds they can hear in their better ear average between 25 and 39 decibels.

People with moderate deafness have difficulty in following speech without a hearing aid. The quietest sounds they can hear in their better ear average between 40 and 69 decibels.

People with severe deafness rely a lot on lipreading, even with a hearing aid. BSL may be their first or preferred language. The quietest sounds they can hear in their better ear average between 70 and 94 decibels.

People who are profoundly deaf communicate by lipreading. BSL may be their first or preferred language. The quietest sounds they can hear in their better ear average 95 decibels or more.
Where do we get information about deafness and tinnitus?

Deaf and hard of hearing people in the UK

There are estimated to be about 9 million deaf and hard of hearing people in the UK. The number is rising as the number of people over 60 increases. About 698,000 of these are severely or profoundly deaf. 450,000 severely or profoundly deaf people cannot hear well enough to use a voice telephone, even with equipment to make it louder. People who cannot use voice telephones might use textphones or videophones.
Deaf and hard of hearing children in the UK

Deafened people

The term 'deafened' describes people who were not prelingually deaf, but have become profoundly deaf in adult life. This often happens suddenly as a result of trauma, infection or ototoxic drugs - drugs that can cause hearing loss.

There are an estimated 123,000 deafened people in the UK aged 16 and over. They often rely heavily on lipreading and written communication. They may require communication support, such as speech-to-text reporters, lipspeakers or notetakers, in meetings and other situations where lipreading is difficult.
Deafblind people

How age affects hearing

Most of the 9 million deaf and hard of hearing people in the UK have developed a hearing loss as they get older. Only about 2% of young adults are deaf or hard of hearing. Around the age of 50 the proportion of deaf people begins to increase sharply and 55% of people over 60 are deaf or hard of hearing.

Are men and women equally likely to be affected?

From the age of 40 onwards, a higher proportion of men than women become hard of hearing. This is probably because more men have been exposed to high levels of industrial noise. Among people over the age of 80, more women than men are deaf or hard of hearing. This is simply because women tend to live longer than men, not because women are more likely to become deaf.

How many people use hearing aids?

About 2 million people in the UK have hearing aids, but only 1.4 million use them regularly. There are at least another three million people who do not have hearing aids but experience significant hearing difficulties in everyday life. They would be likely to benefit from hearing aids.

How many people use British Sign Language (BSL)?

Many people who are born deaf or are deafened early in life use sign language to communicate. It is difficult to say how many people in the UK use BSL as their first or preferred language - current estimates suggest 50,000.

How many people lipread?

It is difficult to say how many people lipread. Everyone lipreads to some extent, especially in noisy situations. When you speak to someone their facial movements will give you information to help you understand the meaning of what they are saying. If you have a hearing loss the balance between what you hear and what you see changes. As your hearing gets worse, you will get more information through lipreading. The biggest group of lipreaders is hard of hearing people.
Deaf people and work

About 3.5 million people of working age - 16-65 years - are deaf or hard of hearing. 160,000 of these are severely or profoundly deaf.

The register of deaf and hard of hearing people in England

In England deaf and hard of hearing people can register with their local social services department. This is voluntary and many people do not register. People are entitled to help from their social services Department whether they are registered or not. This means the figures should be treated with a great deal of caution.

In 2001, only 194,840 people in England were registered with their social services department as deaf or hard of hearing. As there are more than 7 million deaf and hard of hearing people in England, and 577,000 of them are severely or profoundly deaf, it is clear that the registers are a very poor guide.

The figures are published by the Department of Heath. The report is called People Registered as Deaf or Hard of Hearing Year ending 31 March 2001, England.