Anechoic Chamber Cut-off frequency

[mert1]

How can I calculate the lower cut-off frequency of an anechoic room?

Thanks.

 

[GregLocock]

Grab a copy of Beranek.

The trouble is, it won't really help very much.

Your wall treatment (typically, but not necessarily wedges) will have some sort of low frequency cut off, but also the room itself will have its own characteristics (where Beranek will definitely help).

It may seem odd, but the only two I've worked on we actually proportioned as if they were reverberant rooms, to get an even spread of modes.

Are you going to be measuring the results as well?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[mert1]

Is there any way to determine the cut-off frequency with tests or taking measurements?
Thanks

 

[MikeyP]

You need to decide what is an "acceptable" amount of reverberation. Then measure the reverberation time in each 1/3 octave band.

M

--
Dr Michael F Platten

 

[GregLocock]

Yes. As usual it all depends on what you want.

In my case we wanted to how much the rate of attenuation with distance was affected by the corners, so I stuck a sound source in various appropriate places and plotted the resulting SPL field.

Another use for SACs is sound power determination, so I looked at the intensity field around the measurement location. If the SAC had been perfect then we'd see no reverberant component.







Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.