Noise, by definition is unwanted sound. People living
in cities or near roads are used to an amount of background noise.
Noise can be annoying. If the noise is unnecessary, for example
produced by a neighbour playing music loudly, then it can invoke anger.
Noise can damage a person's quality of life, for example if he/she
are unable to sleep well because he/she lives near a busy road.
When exposed to high levels, noise can even be physically
damaging to a person's ear, causing deafness.
The noise can be produced by sources such as machinery or
a can be reduced by three different
approaches. The most effective way to intervene is at the
design stage; if the noisy component can be redesigned to produce
less noise then this provides the best starting point when the
component is manufactured. The redesign of the component could
be carried out by producing a sequence of prototypes. However,
this could be costly in terms of both time and money. Hence
over the last 30 years or so methods have been developed
for the design analysis of structures. This requires the
computational modelling of both the vibration of the structure
and the acoustic response.
It is a fact of life that many components produce the
Environmental Noise
that we have to live with near machinery, roads, airports etc.
Books on Environmental Noise are listed on
science-books.net .
A relatively modern technique of noise reduction is that of
anti-noise or
Active Noise Control. This involves producing
a sound that is similar to, but out of phase with, the noise.
A process of cancellation apparently reduces the original noise.
More obvious methods of noise reduction, or passive noise control,
involves such techniques as insulation and noise barriers.
Books on Noise Measurement, Modelling and Control are listed on science-books.net