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Re: [Phys-l] frequency and wavelength of sound in air

Ah, yes. I attended a week-long physical acoustics class at Monterey one summer. Visiting the Postgraduate School was fascinating for me.

There definitely are frequency doublings which can (and do) happen in acoustics. The amount of doubling is a sensitive probe of material properties; additionally, there are ALL SORTS of uses for the parametric beams which can be produced by an f-doubled setup. I'm quite certain there is a lot of interest in using these beams for the same thing that the Postgraduate School uses the thumper for.

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________________________________
From: Bernard Cleyet <bernardcleyet@redshift.com>
To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
Sent: Sunday, April 5, 2009 2:16:31 AM
Subject: Re: [Phys-l] frequency and wavelength of sound in air

This is a lab at the Naval Postgraduate School in Monterey. The
boxes (no tops) are lined w/ acoustical foam*. Two piezoelectric
transducers are used. Not surprisingly, the labs are heavily
weighted to ocean acoustics. They not only have three large pools in
the basement, but also a rather good home made anechoic chamber and
one lab. room is used as an echoic chamber. They also have a large
sand pile w/ piezo detectors and a thumper. I leave it to youall to
guess its purpose. [hint: the trailer for analysis and thumper
driver reminds me of those used to find oil.]

* can only be used for a few hours before becoming impregnated w/ water.

bc's first job was topping up and running the filtering system
periodically.


p.s. I wonder is there is an acoustical frequency doubling, etc.
analogous to that in optical non-linear crystals?


On 2009, Apr 04, , at 20:19, curtis osterhoudt wrote:

Yes, a standing wave can be established in a nearly-1D water
channel; however, if you are referring to a surface wave (as at the
air-water interface), the behavior is quite complicated (but
understandable, and fascinating, to good undergraduates).

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