Natural Science Forum / Physics / Acoustics / December 2004

Anyone have any experience with Noise Meters microphones?
<http://www.noisemeters.com/accessories/capsules.asp>
Those prices look waaaaaaay to good to be true.
Tech specs: <http://www.noisemeters.com/pdf/class%2Btech.pdf>

If a source makes a sound, and no one is there to hear it, is there an
impact?
This might be more of a legal issue than a noise issue, but I'm curious
to know if anyone has faced this issue.

Hi, I'm working on a semester project on sound source localization,
where my aim is to determine the position of the source of a sound
using  two microphones and estimating the time delay of arrival. But,
how do I process the signals from the two microphones???

If you were to treat a noisy restauant with sound absorbent material to make
it more pleasant for customers, what tests could you do before and
afterwards to prove objectively that there had been an improvement?
In the case I am thinking of, it is a very large restaurant with many

The cheapo radio shack sound level meter only goes down to 50db, but
my application really requires levels down to 20db or 10db. I've found
several sound level meter models that cost around 10 times as much as
the radio shack one but they still only go down to 30db. Is there

I have build an amateur phonometer,
where can I get sounds,of known power ,to calibrate it?
Thanks!!

What's the point in calibrating at 250/251,2 Hz? How was that frequency selected?
Have it any connection with minimum of noise level on that graph:
http://dm-test.narod.ru/graph.jpg (~80 kbytes image)
from the "Microphone Handbook" by B&K?

I'm trying to calculate the resonance of a note at different octaves...
I hope I'm using the correct terminology! What I mean is, I know that
Middle A is 440hz, so what I want to learn how to do, is to calculate
what frequency the "A" in the octave above is in hz... and below... ...

I propose that perhaps certain sloping beaches, in certain
acoustic frequency range(s), effectively form absorbing boundary
conditions that confuse whale navigation and contribute to
whale beachings.