What would the world be like without sound? All of us can imagine to some extent what it would be like to be blind – we simply have to shut our eyes.
It’s much more difficult to imagine being unable to hear speech or music or the dawn chorus, or even the clatter when you drop a pan or your own ‘ouch’ when you stub a toe.
There may be sounds that you would rather not hear – the throbbing music leaking from a fellow passenger’s headphones, the road drill outside your office window, the car alarm that goes off at two o’clock in the morning, your nextdoor neighbour’s lawnmower disturbing a lazy summer afternoon in the garden… yet wouldn’t it feel strange if you couldn’t hear them?
Follow on for our self-test questionnaire to find out if you have a hearing problem.
Do you have difficulty hearing or following what is being said in the following situations?
- Listening to the television when the volume is adjusted to suit someone else.
- Talking on the telephone.
- Having a conversation with someone in a busy place, such as a street, shop or restaurant. Having a conversation with several people in a group.
- Listening to someone against a background noise, such as a whirring fan or running water. Having a conversation when you can’t see the other person’s face full on.
- Talking to women or children – even though you can hold conversations with men without any difficulty.
Do you often:
- Ask people to repeat what they’ve said?
- Misunderstand what people say?
- Agree or nod even when you’re not sure what’s been said?
- Feel that other people mumble when they talk?
- Turn up the radio or television to a volume that others say is too loud?
- Have to watch other people’s facial expressions or lip movements to understand what they say?
The world is, by and large, such a noisy place that relative calm and silence – which are important for our general wellbeing – have become rare treats to be relished.
But as we get older, the world may become uncomfortably quieter if certain important sounds are more difficult to hear – for instance, the telephone ringing, a grandchild crying or the best moments of a favourite symphony.
Even minor degrees of hearing loss can cause intense frustration –when you have to strain to hear what other people are saying, miss crucial spoken information such as station announcements, or feel left out in social situations because you can’t follow conversations if there’s a lot of background noise.
Yet, even if a certain amount of hearing loss is inevitable as we grow older – and it’s by no means certain that it is – there is much that can be done to protect this vital sense and there are many causes of hearing loss that can be treated.
In this section you will learn all about your ears and the remarkable process of hearing.
You will find out why balance disorders may result from ear problems and about other symptoms, such as tinnitus (a persistent, irritating sound in the ears), which can accompany them.
Because you’re concerned enough about your senses to be reading this, you will no doubt want to take steps to preserve your hearing and your enjoyment of the sounds of life – for life.
Sound is measured in decibels – a term derived from the Latin for ‘ten’ plus the name of Alexander Graham Bell, the inventor of the telephone, and shortened to dB.
Any sound-measurement scale has to include a huge range of sound intensities, from a ticking watch to a jet aircraft taking off – a difference of 200,000,000,000 times – so scientists use a logarithmic or ‘log’ scale, which means that every increase of 10 dB represents a sound that is ten times as loud.
Whether noise causes hearing loss depends both on the intensity of the sound and the length of exposure.
On the decibel (dB) scale, 0 dB is near-total silence, but 10 dB is ten times more powerful, 20 dB is 100 times more powerful, 30 dB is 1,000 times more powerful, and so on.
A hair dryer at 80 dB is a hundred times as loud as normal speech at 60 dB.
A rock concert booming out at 120 dB is a million times as loud as normal conversation.
Decibels (dB) Sound
0 Near silence
20 Ticking watch, rustling leaves, quiet room at night
37–45 Computer hum
50–65 Dishwasher, washing machine
60 Normal conversational speech
65 Average city traffic
Difficult to concentrate
70 Television, busy office, noisy restaurant, vacuum cleaner
80 Hair dryer, alarm clock, heavy traffic, shouting
Hearing impairment on prolonged exposure
90–95 Lawnmower, busy pub
95–140 Loud car stereo
100–120 MP3 portable music player
Painful even on brief exposure
110 Chain saw, pneumatic drill, nightclub/disco, baby crying
110–120 Ambulance siren, jet aircraft on take-off
130 Thunderclap, machine gun
Possible irreversible hearing loss
119–140 Heavy-metal rock band
164 .357 Magnum pistol
If our ears are designed to detect and interpret sound, why is it that noise can be so harmful?
Surely, being sensitive to noise is what ears are for?
Well, not quite.
Our ears evolved to pick up biological sounds, not the roar of engines and the din of amplified electronic sound.
Our remote ancestors needed to hear relatively quiet noises that could be crucial for survival, such as the approach of a wild animal that could be hunted for food or might be intent on eating you.
The loudest sound was probably the odd thunderclap, and even occasional loud noises were interspersed with long periods of relative silence.
How is your hearing coping with the cacophony of the modern world?
If you want to do a quick self-assessment, you can take a simple hearing test online that was produced by the University of New South Wales (www.phys.unsw.edu.au/jw/hearing.html).
Most medical professionals believe that age-associated hearing loss, known as presbyacusis, is to an extent inevitable.
But studies of a Sudanese tribe called the Mabaan, who live in quiet rural surroundings, show that they have much better hearing than Westerners – indeed, even older members of the tribe have better hearing than 20-year-olds living in industrial societies.
What’s more, among the Mabaan there is little difference between the hearing of young people and the tribal elders.
Apart from their quieter life, the Mabaan people’s excellent hearing may be influenced by their diet – a factor discussed in the next chapter.
Meanwhile, all the evidence seems to suggest that it is well worth protecting ourselves and our children from the potentially deafening effects of loud noise.
The more prolonged your exposure to noise and the higher the volume, the greater your chance of hearing loss, but once the exposure ceases no further damage will be done.
If you notice hearing loss after exposure to loud noise, it will usually (but not always) improve in the following hours or days.
Here are ten ways to limit avoidable noise as much as possible, and safeguard your ears when exposed to unavoidable noise:
• Limit the time that you spend listening to noise for entertainment.
• Reduce volume levels on stereos, TVs and iPods.
• If you use an MP3 or iPod, wear in-ear filters to cancel out background noise.
• Wear proper earplugs or earmuffs whenever you cannot avoid exposure to loud noise, for example when mowing the lawn or using power tools; cotton wool and other homemade plugs are ineffective.
• When in a noisy environment, try to go elsewhere for regular short breaks.
• Distance diminishes the effective decibel level that reaches the ear. Get as far away as possible from unavoidably loud sounds – don’t sit or stand next to loudspeakers at a concert, for example.
• If you are provided with earmuffs at work, use them.
• Keep your car windows closed when driving on busy roads.
• Reduce outside traffic and other noise in your home by, for example, installing double glazing, hanging heavy curtains or planting trees or shrubs between you and the road.