Natural Science Forum / Physics / Acoustics / September 2004

i don't seem to be able to post, so this is a test.  
is there a time lag inherent in the process here?  for an admin to approve, etc.?

Suppose there are two layers of liquids 1 and 2. The acoustic
impedance in Fluid 1 is Z1 and is Z2 in Fluid 2.  Assuming Z1 = Z2 but
the sound speed c1 is not equal to c2. Is it possible to detect the
boundary of Fluid 1&2

In a recent post I pointed out that the standard plane wave solution of the
linear wave equation for sound creates a time-average mass transport in the
direction of propagation, which (I postulated) must be corrected by adding a
constant velocity in the opposite direction. Ken ...

I'm interested in the behaviour of airborne particles in the 0.1 to 10 micron
range, in response to sounds from 100Hz to 100KHz.
What is the peak velocity of the particles as a function of particle diameter,
particle density, sound frequency and sound intensity?

Does anyone have any information on training humans or animals to
recognize/identify sounds of machines, vehicles, and mechanical
devices?
Thanks

Acoustically speaking, how is a chord different from a single note? If a certain
acoustic event is produced by simultaneously plucking two or more strings on
(for example) a guitar, could the same event be produced by plucking a single
string on another guitar that was tuned ...

Does anyone know an any successful applications of active noise
cancellation in a boat cabin to reduce engine noise.  The boat in
question has a rectangular 24' x 40' cabin with two diesels in an
engine room below.  The floor is steel.  I realize that this may be

Hello to everyone,
I posted this message some days ago on another newsgroup, but after
thinking and reading a little more literature, I thought that the
subject could be more appropriate for this newsgroup.

I am currently taking physics courses, at my advanced age of 65, at UC Santa
Barbara, which has an absolutely first rate Physics department. One Ph.D. is
all I need, so I am doing this just to keep my brain from rotting. At UCSB
you can learn all about quantum mechanics and string ...

In standard IEC 1260, chapter 5.6 describes how to test 1/1 or 1/3 octave
band filters for real-time operation. It is basically to perform a frequency
sweep and then compare measured results with theoretical-calculated values.
Chapter 5.6.5 says: logarithmic frequency sweep rate ...

I will show that in a tube any piston velocity function will
be exactly transcribed (i.e., without distortion of any
kind) to a propegating wave.
(0) Given:

I am thinking of using BSWA type1(MP201) and type2(MP206) microphones in my
project. The URL to their site is
http://www.bswa-tech.com/products-mp201.htm
Does anybody here has some experience with this company and this

I've live in an older condominium, and I have the pipes for my
downstairs neighbors' (3 units) heat pumps running vertically through
a chase in my bedroom.  When we upgraded the heat pumps to more
powerful, scroll-compressor units, they started transmitting a lot of

I often have to predict reverberation time in rooms like classrooms,
gym, open offices and so on. I use Sabin's formula though I know it's
wrong but it's simple to use and it's not a catastrophy if the results
aren't exactly as predicted. BUT, I'd like to do better by using a