# What's the relationship between the amplitude and the Sound power level?

1. Dec 27, 2011

### MrMeltedChees

Okay, so I have a sound wave (a visual representation). From this I can see the amplitude of the wave, However, I need to know what the sound power or the sound pressure level. Could someone please give me a formula that could help?
Thanks

Last edited: Dec 27, 2011
2. Dec 27, 2011

### Simon Bridge

You are asking something quite complex and your terms suggest you are not clear about what is going on.

A sound wave is usually thought of as pressure variations in some fluid like air - though it can also be vibrations in a solid. So the wave itself is the pressure level - though you may have a description of it in terms of longitudinal displacements, in which case you need to translate the displacements into pressure.

A single note would give you a sinusoid with a constant amplitude. The magnitude of the wave may vary with position and with time for a fixed position.

The wave can also be represented in terms of energy - the parts where the medium is moving most has the most kinetic energy for example.

So before you start, you need to know what it is that is being measured.
A microphone, for example, measures changes in air pressure.

Possibly what you are looking for is something like this: