Re: dispersion at Chichenitza

[kyle forinash <kforinas@IUS.EDU>]

> At 10:47 AM 1/10/00 -0500, kyle forinash wrote:
> > there is a distinctive chirp in the echo; lower sounds
> > return faster creating an echo that rises in pitch.
> ...
> > Does anyone know exactly how this works?
>
> If you had reported a sound that *falls* in pitch there would be a
> beautiful explanation.  It would be a great demonstration of
> diffraction-grating physics.

It pretty much sounded like a rise to me (but no one said I have
perfect pitch!). The first half of a wolf whistle.

If I had stood in one spot and heard only the low notes coming back
and then heard high notes at a different location I would have said
diffraction. But I didn't move. I don't see how diffraction changes
the speed of return. Dispersion does this but I don't see why the
steps cause dispersion.

> You don't need to travel to the Yucatan to observe acoustical
> diffraction.  Any building with exterior lattice-work on a sufficiently
> coarse scale will do nicely.  Actually most such buildings are nicer than
> pyramids, because they give you more options as to the angle of incidence.
>
> ===========
>
> If you really are reporting a sound that *rises* in pitch I have no idea
> what is going on.
-----------------------------------------------------
  kyle forinash   812-941-2390
  kforinas@ius.edu
  Natural Science Division
  Indiana University Southeast
  New Albany, IN    47150
  http://Physics.ius.edu/
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