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energy of a sound wave


How do you describe, simply, the energy in a sound wave. If the loudness of sound is the amplitude and the frequency is the pitch then I am assuming, possibly wrongly, it takes more energy to create a louder sound and a higher pitched sound. Or perhaps you can't equate energy to a sound wave like this`

As a sound travels it gets quieter. Is this because the sound has lost energy or it has been absorbed by air/other materials.

Can sound lose pitch as it travels?

Math / Science

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8/22/2022 - Mon

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Dave Baldwin

Sound is a pretty mechanical event.  The fact that it is often repetitive at a certain frequency makes it seem different but in fact, the whack of a hammer is a sound that doesn't necessarily have a frequency or repetition.  Sound get quieter with distance because it loses energy through being absorbed by and air and materials.

Pitch / frequency is set by the mechanical action at the source.  I have never heard of pitch being changed by distance itself.  Perception is changed by the intensity and if the source moves, the pitch changes at the point of a non-moving observer (Doppler effect).
Dave Baldwin

@aburr is right, I forgot about the square-law effect where the energy density gets lower because the sound spreads out from the source.

'energy density gets lower' is way too confusing for school kids but at least I know the correct terms. School books tend to say 'sound gets quieter as it travels because it is absorbed by other media'
Is it ok to say that as a simplification? I try and observe the correct language where possible.
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William Peck

"School books tend to say 'sound gets quieter as it travels because it is absorbed by other media'
Is it ok to say that as a simplification?"  not really        It at least is not untrue
Perhaps you could say that the sound gets quieter because it is spread out over more space.

thank you!