The impedance of a sound wave in a tube ?

[wolf69]

Sound wave in a tube..

Hi

The impedence in a medium for a pressure wave ( a sound wave) is in relation to the phisycal characteristics of the medium.
For example for the a gas I found:
Z = speed * density.

Now think at a pressure wave traveling through a tube (pipe); the impedence should be the same at open air since the medium is the same.
But when it reaches the open end pipe it is reflected in such way (in many musical instruments it is the working principle).

So I think there is a impedance changeing.. but the medium is the same!
Where is my mistake?

Bye all!

 

[Ahmed Ragab]

Re: Sound wave in a tube..

well mainly this is called the waveguide effect, the tube acts like a guide to the pressure wave inside.

thus actually the impedance of the medium is the same it doesnt change... what does change is the impedance affecting the wave itself due to being trapped inside the tube

 

[wolf69]

Sound wave in a tube..

So the wave inside is moving on a different than air impedence.. maybe wave's speed change? Is there any formula telling this?

Bye!