Noise Pollution

Now we have a unit to measure with - the dB - we might want to think about what we want to measure! We've noted that sound equipment is often specified using dBs, and sometimes this equipment is responsible for creating unwanted sounds - noise - in our environment.

Environmental noise pollution doesn't just come from neighbours sound systems, car stereos, pubs and clubs etc - it can result from traffic noise, trains, planes, factories, ice-cream vans and mobile ring tones too!. People in the UK live pretty close together on average, compared to many other countries, and this means that we can easily drive each other nuts - not least by making noises that other people find objectionable.

Noise is measured using a sound level meter which gives readings in dB.

sound level meters

There are many regulations and laws to control the amount of noise that is acceptable, and the enforcement of these laws often comes down to Environmental Health Officers working for your local council. Ideally, noise can be 'designed-out' of a situation during the planning stage, but very often planning goes wrong and then sorting out noise pollution can get very expensive.

For example, people living next to a busy road or railway line often experience noise. If this noise is too disturbing, there are several methods to make things quieter. These include placing barriers between the house and the noise source to help block the sound, or fitting double glazing to stop the sound travelling through the windows of the house.

Noise pollution and its effect on learning in schools and colleges has become a big issue recently, and acoustics plays an increasingly important part in the design of new buildings for this purpose.

Noise sources near a concert hall

The many sources of envrionmental noise that has to be prevented from entering a concert hall.

Hearing Loss

Noise isn't just annoying - sometimes it can be dangerous. Before regulations were imposed to control noise levels in factories, people often became deaf over time due to noise exposure at work. You may know older relatives who have trouble hearing - everyone's hearing deteriorates with age, but noise exposure can make this much, much worse.

Diagram of the ear

Today, workplace noise is controlled in law, and people who work in noisy environments often wear ear defenders to cut down noise levels as shown in the picture below.

Someone drilling with hearing protection

So - you might think that 'noise-induced hearing loss' is a thing of the past. Unfortunately this is not true - exposure to a high level of any noise can cause temporary deafness, and repeated exposure over a period of time can cause permanent hearing loss. This includes exposure due to personal sound equipment (MP3 players over headphones etc) as well as music exposure at clubs and gigs.

Whilst many people might consider it a little eccentric to go for a big night out wearing industrial hearing defenders, small ear-plugs are widely available and are very widely used by people whose hearing is essential to them - musicians, mix engineers, broadcasters and so on. The days of the deaf sound-man should be over...you might want to think about your own noise exposure...

Wave Types Test

Question 1

What form of wave is shown below:

Slinky moving perpendicular to the direction of travel of the wave.

Longitudinal

Transverse

Wavefront

Amplitude

Question 2

Which of the following is a transverse wave?

Hair Wave

Shock Wave

Sound Wave

Radio Wave

Question 3

Express the number 5 in the form Log10x

Log105

Log1050

Log10100000

Log101000000

Question 4

Log [a/b] is equal to:

log a - log b

log a + log b

log a / log b

log a - b

Question 5

A sound generates 0.5 W m-2. What is the intensity level in dB?

50dB

108.2dB

117.0dB

120.0dB

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