Natural Science Forum / Physics / Acoustics / December 2004

Hi everyone,

I'm currently writing a program to simulate
the acoustics of my room and was hoping to
get some help from people more knowledgeable
than I.
What I am doing is solving the wave equation PDE
for the pressure for a rectangular room, using
a Matlab program I've written, which, in a rather
"bang-my-head-against-the-wall" manner divides my
room into a finite grid and solves for pressure
at (ijk) according to its neighbours in (i+1,j,k),
(i,j+1,k), etc ... very simple-minded.
My problem is - what should my boundary conditions
be if I want to apply frequency-selective absorption?
(i.e. use tables of known absorption coefficients of,
say, wood, glass, concrete, carpet, etc ... )?
And are there any better ways of carrying out the
simulations? I've read a bit about BEM, TLM, Digital
Waveguides and a host of other methods, but I don't
see any obvious advantange, except perhaps time
efficiency - and I should add I don't really care
waiting a couple of hours for the results of each trial.
Also, if there are any specific books/papers/links/PDFs
that provide a simple introduction to these topics, I'd sure like
to hear about them.

Regards,
And many thanks,
Assaf.

PS
I am a working physicist (MRI/NMR), I'm not afraid
of math, actually quite fond of it ;). Acoustics is
just a "side hobby", but I can handle technical
explanations as well as the next physicist. I also
have access to many technical journals through my
workplace, so if you have specific references I'd
welcome those too!