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