# Soundwaves question

1. Oct 26, 2009

### Denver Dang

A little question I hope you can help me with.
If you got the low frequency bass notes and some high notes as well.
Then you have the formula:
v = $$\lambda$$*f

A quick calculation gives you a wavelength of 34,3 m for af 10 Hz soundwave and 1.715 cm for a 20.000 Hz soundwave.

Does that mean that I would need a 34,4 m wall to stop the waves of a 10 Hz soundwave, if we imagine that wall being infinitetly tall and wide, and then only 1.716 cm wall to stop the waves from a 20.000 Hz soundwave ?

Or is there some other factors that play along ?

Regards

2. Oct 26, 2009

### billiards

Presumably you worked out the wavelength in air.

Have you thought that the speed of sound might change in the wall?

3. Oct 26, 2009

### Denver Dang

I've thought of that yes. But do you have to calculate the wall-thickness depending on the material that the wall is made of ?
So if the wall is made of material that doubles the speed of sound, compared to air, the wavelength doubles and you need a thicker wall ?
Or is it a mixture of both ? :S

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