Sound
Question
How does sound behaves, propagates ?
Purpose
The purpose of this question is to get a clear picture what the physical behaviour is of sound, compared to the behaviour of how electromagnetic phenomena propagate and the behaviour of how gravity propagates.
Answer
Sounds behaves, with relation to speed of propagation, very similar compared to electromagnetic and gravity propagation.
Instantaneous sound propagates in a sphere around the source, independent of the speed of the source.
Specific I use the word instantaneous sound. Instantaneous sound is a disturbance generated at one single instant, the smallest time increment. Our ears do not hear sound from one single instant, but always something over a certain period of time. As a consequence what we hear is influenced by the speed of the source and the speed of the observer. This is reflected in a change in frequency of what we hear.
However there is more. Sound is a disturbance of air, which is influenced by wind. That means you should only compare sound with light when there is no wind.
A good way to study sound and light is when you can hear and see an aeroplane. Neither the direction in which you hear nor see comes from the true position.
In order to compare the behaviour of sound, electromagnetic and gravity, a simulation in the form of a program in Quick Basic is supplied.
To order to get a copy select:VIRTUAL.BAS
Feedback
None.
Last modified: 29 December 1995
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