Natural Science Forum / Physics / Acoustics / January 2004

Could anyone give me some information about how to calculate the
force/moment induced by an incident sound pressure?
I guess the principle of virtual work should be utilized to approach
this problem, but it is hard to find references on this topic.

I am using a Bruel & Kjaer 2238 SLM for some time and I would like to know
how some parameters are computed.
The displayed values are updated every second, whatever the time weighting.
So if for instance I am trying to get the Lp with a fast (125 ms) time

That question concerns at first Europeans but that would probably
concern other people that use ISO's calculation methods for
environmental noise.
I'm wondering about how the Harmonoise project will end up and I'd

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Follow the directions below and in two weeks you could have up to
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I am going to buy a program to simulate acoustic events in external sites.
Who is the best program between Mithra and Cadna?
Distributor tell me Cadna is more modern and allow updating.
I want simulate roads, railways, airports, industries, and cities.

Does anyone know of a software based graphic equaliser or filter that
replicates the ISO standard 1/3rd Octave points.
I would like to be able to set the equaliser to the same intervals
as the ISO standards so as to pass a pink noise though it and

If you want to erect glass partitions in a large open space office,
say 2500 m3, for the reduction of SPL and hence reverberation time, is
it possible to calculate the reduction in the afore mentioned
acoustical parameters before the physical implementation of the plan?

Can you give me hints on where to find acoustical properties af railway
ballast (e.g. frequency dependant absorption)?
Thanks for your help
Erich Meisterhofer

I am working for a machine, which produces high frequency noise.
(2000Hz & above). I am using AutoSEA for this analysis. I don't have
any measurement data. One electromagnetic load of some magnitude at
50Hz is the only input available.                  My queries are:

I'm sure everyone is aware of dummy heads equipped with artificial
pinnae used for binaural recordings and research purposes. I'm wondering
if it's possible to buy a set of artificial pinnae (without the head,
I'm not concerned with the HRTF). A quick Google search didn't turn up ...

In loudspeaker design it is often referred to a diffraction effect
which originates in this: A box mounted driver radiates in half space
at high frequencies but full space at low frequencies. This effect
leads to a raise of the response of 6 dB for high frequencies,

I am designing a metal perf panel to absorb an octave centered at 250
Hz.
I was checking the formula for perf panels which I use.  It is as
follows:

I believe it is possible to estimate the contribution from a path via one
partition, to the sound breakthrough between one room and another, by the
following method:
(1) Hit the partition in question with a hammer, measure its velocity with

Does anyone have any test data for Huppe demountable partitions
(European product)?  One has been specified for a project of ours but
we can't seem to get any data?  We need an FSTC 50.
Thanks in advance for any help.