Distance Travelled by a Soundwave?

[Serpent7]

Hi there, nice forums, and nice to potentially meet you (if 'meet' is the right word online).

 

I have a question that I cannot answer, and cannot find any information on:

 

What is the relation between frequency (pitch) of a soundwave and the distance it will travel before becoming inaudible? Any help appreciated, thankyou.

[RyanJ]

Hi there' date=' nice forums, and nice to potentially meet you (if 'meet' is the right word online).

 

I have a question that I cannot answer, and cannot find any information on:

 

What is the relation between frequency (pitch) of a soundwave and the distance it will travel before becoming inaudible? Any help appreciated, thankyou.[/quote']

 

You could say (maybe?) that because the higher piched waves have more energy (From [math]e = hf[/math], greater frequency = greater energy) they travel further.... not shure if thats right but thats all I can think of right now

 

Cheers,

 

Ryan Jones

[swansont]

If it's a point source making a 3-D wave, the sound intensity should drop off as 1/r² based on geometry. However, loudness depends on the amplitude, and the intensity is amplitude²This and the included links might be of some help.

 

The frequency response is proportional to frequency²Here (scroll down a little) is an explanation why, when a stereo-booming car goes by, you hear the bass better than the treble, because of the attenuation. The actual frequency response (i.e. the constant in the proportionality) is going to be different for different materials, and at some high frequency, I'd expect the response to deviate from f², just because the atoms can't vibrate fast enough.

 

You haven't defined all the things that are relevant, though. Is "inaudible" a set amplitude or is it dependent on the ear's response function? Certain frequencies will become inaudible not just because the amplitude has dropped off, but because the ear's response isn't as good.

[Serpent7]

Okay, well, this question stems from a project I've been looking into recently- ând inaudible, in this case, refers to sound below 60dB. I didn't think it as relevant, but there you go. And yes, I (believe I) know, 60dB is audible to the human ear in most cases (with common frequencies, anyway).

 

The project involved generating a sound at a certain pitch and measuring the distance it travelled before a decibel counter registered a reading under 60dB. I want to know, in order to back up my findings, what relationship there is between pitch and this distance.

 

Thankyou for your help so far, btw.