Natural Science Forum / Physics / Acoustics / November 2005

Can anybody help me with a problem.  Supposedly, there is a 180 degree
phase shift when a hydroacoustic waves encounters the air interface at
the underside of the sea surface.
First, is this indeed the case?

The natural frequency of a cylindrical organ pipe is elementary, dear Dr
Watson: open 2 ends: L = lambda/2, closed 1 end: L = lambda/4.  BUT, what is
the change of diameter like in a trumpet do?  And how about change of
direction, the simplest that looong Swiss mountain horn which ...

Can anybody point me to a paper/book/site/algorithm/tool on how to
desing a low order filter to model the absorption coefficients of
materials. I have found that these coefficients usually are given for 6
octave bands (125,250,500,1000,2000,4000Hz). More information on this

I'm searching for info on how to acquire acoustical parameters (like
RT60) of a given (simple) virtual room for a late reverberation algorithm.
I've read some text that suggests using a ray tracing based method for
doing this, but i dont quite understand how exactly i should get ...

Can resilient channel be used effectively over a concrete wall?
I have a concrete block wall in common with the house next to mine and
the amount of sound that comes through is unbelievable.  The other day
I heard the woman sneeze over there and it sounded like it was right in

Can anyone help me get a copy of the algorithm/procedure for
calculating STC and RW ratings.  I have been doing STC and RW
measurements extensively for some time, but since moving I no longer
have access to a written version of the procedure.  I wish to code some

I have an HP iPAQ h4150 PPC (Pocket PC). It has a built-in sound card, but:
the input is built-in microphone only, i.e. no input jack for microphone or
line-in. When taking sound recordings in the field, I often use my notebook
to record the signal from my sound level meter AC ...

I have just completed the construction of a drum practice room in my
garage.  The internal dimension of the room are 2.64m by 3.09m by 2.23m
(W,L,H).  This room fills the full width and height, but only about half
of the internal length of the garage.

How does the absorption of a carpet change as it gets used and the pile is
flattened?  I am guessing that the reduction would be greater on a carpet
with a longer pile depth as the pile would compress more.  I am also
guessing that the change would be greater on a carpet tile with ...

I've read some old posts about furnace noise, so maybe someone here can
help me out.
I have a Trane XE80 gas-fired furnace.  It has two fans in it, the
blower that moves air through the house and an induced draft fan to

ACOUSTIC Engineer
JOB DESCRIPTION As one of our acoustic engineers you will work in Smart
System Sound, Inc. Audio Manufacturing company which designs, develops
and manufactures worlds best Audio sound speakers in Car, home Theatre

Folks,
Does anyone know of any specific research or published papers into the
effects of faulty, damaged or incorrectly worn hearing protection,
particularly for the breaking of seals for ear muffs/ear defenders by

Does anyone know of any good articles/papers/books with good
information on the physics behind acoustic feedback (The Larsen
Effect)? I would specifically be interested in feedback in relation of
guitars to amplifiers. Any help would be appreciated, thanks in

I am currently working on a piece of support equipment, and I need some
assistance regarding sound attenuation.  The unit contains a diesel
APU, generator, electronics, hydraulics, and pneumatics.  All of these
components are located in a 50" cube that is sealed off from the

I wonder if it is possible to convert an audio e.g. as an .au file to a
video file containing its spectrum data e.g. in avi format?
Cheers
Sashu