Re: wind instrument +- filtering of broadband noise

["Bernard G. Cleyet & Nancy Ann Seese" <georgeann@REDSHIFT.COM>]

This sounds similar to the Rijke tube -- you'll get better results, if you put
in the tube a steel screen near the end placed over the burner.  It'll get red
hot and will continue to power the tube after burner shut off.  The reverse is a
refrigerator -- useful in military vehicles.  Also NPS has a model that works by
cooling.

Check archives, at least two threads on this subject.

bc

P.s. Since it'll operate with out the coupling to a burner, it's operation
puzzles me.


Tom McDonald wrote:

> Thanks to all who have contributed to this topic.  It has been very
> interesting.  If anyone has the patience to reinforce my improving
> understanding, I would greatly appreciate it.
>
> I do the probably common demonstration in which a large lighted laboratory
> gas burner, e.g. Fisher burner, is placed on the floor and a long cardboard
> carpet roll  tube is lowered over it until a very loud low pitched sound is
> produced.  Is it true that even though this clearly IS a hissing source,
> there is more going on than "a resonant filter applied to a broadband noise
> source" (from J.D., I believe)?    For example, I picture the air in the
> tube and the gas in the burner flame coupling so that they both vibrate at
> the resonant frequency of the tube.  Is this a reasonable model?  Is this
> "mode locking"?  How do I explain the large increase in sound intensity to
> my students?
>
> Thanks for any help here.
>
> Tom McDonald
> Harbor Springs High School
> Harbor Springs, Michigan