Natural Science Forum / Physics / Acoustics / March 2005

i have a query that i'd like to present to the group about room modes.
our old pals axial, tangential and oblique... Everest offers a
"ranking" system for these, where tangentials have 1/2 the energy of
axials, and obliques 1/4

Can anyone help me? I am trying to understand when the most absorption
occurs in a membrane absorber - typical of a wood panel with damping
and a cavity behind. I can use an accellerometer and either impact
hammer or sound source to get a curve of frequency response. I am

This is not strictly acoustics, (maybe more DSP), but it should be a
familiar problem to many of you. I have recorded vocalizations at 100kHz,
and they have a frequency content from 200Hz to about 35kHz. Unfortunately
(what with old age...) I didn't hear that the TV monitor that we ...

-------- Original Message --------
Subject: New Professor F. B. Farquharson AKA Herr Richard, Maple
Support, Scientific Computers GmbH
Date: 13 Mar 2005 01:49:06 -0800

i am versed in the basic theory relating to forced vibration in a
panel, the traditionally presented stiffness/resonance/mass/coincidence
regions and so forth.
i have seen projects where stiffness is utilized for sound isolation,

http://sound.westhost.com/doppler.htm
Any remote chance that the "anonymous non-believer" is the one, the only,
Bob Cain?  

I had read in physics texts that
sound in acoustic cavities behaved like microwaves in
one sense and heat in another ( wavelength and frequency)
but I forgot which was which.

Can anyone help me? I am trying to understand when the most absorption
occurs in a membrane absorber - typical of a wood panel with damping
and a cavity behind. I can use an accellerometer and either impact
hammer or sound source to get a curve of frequency response. I am

What is a good reference book with formulas for calculating the
transmission loss through a plenum chamber?
Are there any commerical software packages for calculating the sound
propagating through piping systems including plenum chambers?

I'm interested in violin and guitar
resonances and how they amplify sound.
Yamaha has a "Silent violin" , electric violin
that uses electronic simulation to give the "effects"

My water heater is on its way out. Consequently, until I get a new diaphragm
fitted to it, it can take some time between turning on the hot tap, and the
gas coming on, and heating the water.
I have noticed in the bathroom, that when I turn on the hot tap in the

Just to let you know. Here's a very interesting article on acoustics i
open plan offices from the canadian Institut for Research in
Construction:
http://irc.nrc-cnrc.gc.ca/fulltext/nrcc46274/

I'm Back again.
This time I have a different problem....
I tried to record a sinusoidal tone using a pair of microphones by
plugging the microphones into the line-in port of my sound card. I used

Hi friends:
I want to know if is there some matematical relationship between Lavg
(criteria 85 dba and q=5) and Leq (criteria 85 dBA and q=3)
Thanks and luck for all