Transmission loss of structural panels

[elogesh]

Hai,

Is there any standards for carrying out(experimentally) the transmission loss of structural panels.

The concerns are

1) What should be the configuation of sound source?

2) How the panel should be prepared and what should be its

dimensions?(The panel is not having any surface treatment)

3) What about the environement around the panel(free field!!) and how the plate should be supported?

4) Where to place the sound source and microphones?

Is there any web-site regarding the above information?

Is there any formula for calculating the transmission loss of structural panel?

With Regards
logesh

 

[GregLocock]

The only successful repeatable measurements of transmission loss that I have seen have been in specially built sound transmission loss suites. The two I have used have a pair of reverberant rooms separated by a massive wall. The sound intensity in each is calculated by the standard method, from the known decay characteristic of each room. One room is smaller, and has several loudspeakers and microphones in it. The receiving room is larger and just has microphones (I think 6) and reflectors in various odd places inside the room.

There are smaller machines on the market - I have used an APAMAT myself, but it does not correlate very well with the TL suite.

For automotive work we used panels about 1m square, simply supported at the edge. Sealing of the edges is very important.

There are many equations for TL in the literature, depending on the approximate form of your panel, but really the behaviour is governed by the mass law, any subtle tuning effects are superimposed on that. The SAE is sure to have papers on that, but I don't know any reference numbers.

I know that standard reference texts for noise and vibration cover this, I suggest you look them up - Beranek being the obvious source.
Cheers

Greg Locock

 

[otaio]

Thought the following may be of interest:

The full book citation is:

Noise and Vibration Control Engineering: Principles and Applications
Editors
Beranek and Ver
1992 Second Ed

A list of acoutical standards go to:

http://www.industrialacoustics.com/RDMETH.htm

For a description of carrying out the laboratory test go to:

http://www.acoustics.auckland.ac.nz/ATS/ATS_test_list.html#Airborne Sound Insulation

An interesting subscription site is:

http://www.vibrationdata.com/tutorials.htm

Hope this helps
Bob B

 

[MikeyP]

ISO 140 part 3 is the international standard for measuring SRI in a laboratory transmission suite.

Michael