British Tinnitus Association

Andrew McCombe – MD FRCS

The human ears are two, paired vibration sensors lying on each side of the head. They are particularly sensitive to the vibration of air molecules between the frequencies of 20 – 20,000 Hertz. i.e. Sound!

The ear is made up of 3 composite parts:
1. The outer ear is made up of the external ear or pinna (the funny shaped thing on the side of your head) and the ear canal. The outer ear essentially acts as a funnel to focus sound down onto the eardrum.
2. The middle ear is made up of the eardrum and 3 little bones (Malleus, Incus and Stapes) in an air-filled space that connects to the back of the nose via the Eustachian tube. It is this tube that allows your ears to “pop” and keeps the pressure in the middle ear the same as atmospheric pressure. The middle ear transforms the low pressure, high amplitude vibrations of the air molecules into lower amplitude but higher pressure vibrations which are then transferred to the fluids of the inner ear.
3. The inner ear is made up of 2 parts: the vestibule (which includes the semi-circular canals) for balance and the cochlea for hearing. The cochlea is a transducer and converts the mechanical movements of sound into an electro-chemical signal that passes through the cochlea nerve to the brain. This transduction is performed by vibrations of hair cells, both inner and outer, in a part of the cochlea called the Organ of Corti.

Unfortunately, the ear can be damaged by high intensities of the very energy source it was designed to detect. This high intensity is measured in the form of volume: if it is too loud, your ears are at risk. The outer hair cells are more metabolically active than the inner hair cells and so are more susceptible and therefore damaged first. As a result individuals may suffer problems such as tinnitus and difficulties with conversation in the presence of background noise, long before they reach the level of a noticeable hearing loss.

How can you tell if you are somewhere too noisy?
There are two easy ways to do this: If you are exposed to noise that afterwards leaves you with ringing in the ears then it is too loud. This ringing in your ears (technically this is tinnitus) represents a condition called temporary threshold shift and indicates that your hair cells are exhausted from too much noise.

The second way is whether you can hold a conversation or not. A rough guide for background noise levels depending on ability to talk is shown below:
Loud Voice at 4ft - 93dB
Shout at 4ft - 99dB
Shout at 2 ft -105dB
Impossible even close to listener’s ear - Over 110dB
The theory says that for every 3dB increase in sound intensity, the safe time of exposure to that sound halves. So if we accept that 93dB is “safe” for 2-3 hours, then you can work out the rest for yourself!

What can you do to protect yourself?
There are a number of options open to you:
1. Avoid the noise altogether. Not always as easy as it seems. However, if noisy pubs or clubs, or some other recreational activity is causing enough trouble then this may be the only realistic choice.
2. Reduce the time of exposure. This is often an easier and more realistic option. This can either be done by physically spending less time in the noisy environment or alternatively by taking breaks every half hour or so for ten minutes to, literally, give your ears a rest. Or both! Also important for people in hot clubs is the need to take plenty of fluids to make sure the inner ear circulation of blood, and the inner ear fluids, are kept ‘topped up’.
3. Reduce the intensity of exposure. In other words effectively turn down the volume. The best way to do this when out and about is by the use of earplugs. Interestingly (and for a very complicated physiological reason) you may find that you can hear the music (and your friends talking) better with earplugs in than without! Almost any earplug will do as long as it is well fitted and comfortable. Most earplugs have detailed instructions on their use.

And at the end of the day, if you have worries or concerns about your ears or hearing, you should seek medical help, normally from your general practitioner in the first instance.

Reviewed June 2010 © British Tinnitus Association

This information is not a substitute for medical advice. You should always see your GP / medical professional