Date: Mon, 19 Mar 2012 11:36:07

Author: Paul Nord

Subject: Re: echo tube

Post:

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I've heard that it is a dispersion effect. Not only do different =
wavelengths travel at different speeds. But they reflect along the =
edges of the tube at different angles. So the path length for some =
frequencies is much longer from one end to the other. You may pick out =
only those wavelengths that have a resonance in the tube. But with a =
big tube, there are lots of resonances.

Paul

On Mar 19, 2012, at 11:14 AM, George Herold wrote:

> Hi taper's, So I assume most have you have heard an echo tube.=20
> http://exs.exploratorium.edu/exhibits/echo-tube/
> =20
> Clap into one end and you get a 'weird' echo. What's the physics =
explanation?=20
> =20
> (I'm thinking maybe some dispersion of the higher frequency modes?)
> =20
> Thanks,
> George

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I've heard that it is a dispersion effect. Not only do different wavelengths travel at different speeds. But they reflect along the edges of the tube at different angles. So the path length for some frequencies is much longer from one end to the other. You may pick out only those wavelengths that have a resonance in the tube. But with a big tube, there are lots of resonances.PaulOn Mar 19, 2012, at 11:14 AM, George Herold wrote:

Hi taper's, So I assume most
have you have heard an echo tube.
http://exs.exploratorium.edu/exhibits/echo-tube/

Clap into one end and you get a
'weird' echo. What's the physics explanation?

(I'm thinking maybe some
dispersion of the higher frequency modes?)

Thanks,
George

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