Page 4 - Vibrations

The process continues for the other t values.

You will observe this disturbance is propagating along the

tube.

These disturbances are sound waves.

Sound propagation is a series of expansion and

compression of air mass.

High pressure zones and low pressure zones.

If you have a point source, sound

waves will emanate from that point

source in a pattern of spherical high

pressure and low pressure zones as

illustrated on the left.

The distance between the zones is

related to the pitch of the source and

the propagation speed is 343 m/s.

Machines generate a lot of sound waves which are

normally a source of annoyance.

The advent of precision engineering has reduced the

average amount of sound a machine generates.

Cars today are much quieter (on the inside) than cars

made 30 years ago – all due to a greater understanding of

the source of noise and precision engineering.

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