Anechoic Chamber+FFT 2

[par1]

Our sister company is planning to purchase Anechoic Chamber, FFT/Microphone to develope sound lab so is there any recomedations? (deal with components like Intak manifold)

Thanks in advance,

 

[GregLocock]

make sure your anechoic chamber is large compared with the test components. Don't trust calculated cut-off frequencies. I'd defineitely get one designed by someone who can show you measured frequency response curves for one they've designed. Good luck. Failing that you might as well design it yourself, the average architectural acoustic consultant hasn't got a clue about designing anechoic chambers.

Is it going to be anechoic or semi-anechoic?

For fft analysers I have listed a few in the FAQ



Cheers

Greg Locock

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

 

[fwcatr]

par1,

I was looking to replace our anechoic chamber a few years ago. One thing you want to keep in mind is make sure you tell them what you want the chamber to be, don't let the anechoic chamber manufacture tell you what you want. If they can't make one per your every specification, find someone else.

Search the internet for acoustic chamber/enclosure makers in your area and start there.

I was working with three different makers of sound enclosures and they seemed to be able to make the thing just like I was telling them, but we never bought one, so I don't really know if they could have come through on what they were telling me.

What are you going to be measuring with your chamber?

Regards,
Fred

 

[par1]

Thanks Greg Locock & Fred for your help.
Currently, the plan is to test underhood components like Air Intake, Manifold for Intake Noise.

As long as I know that Semi-anechoic is little bit cost saving than Anechoic one, but still need to talk with Noise Consultant to select for underhood testing.

Please share if anyone has experience with Underhood copmponents.

Thanks again,

 

[SomptingGuy]

par1,

Are you looking to measure orifice noise (engine pulsations, plus flow noise) or shell noise (noise radiated from casings)? If it's orifice noise, think about getting hold of a good baffle board too.

 

[friartuck]

Just a minor point. I used to work for a fan company who purchased a semi reverberant chamber. It was used for testing fans.

Unfortunately the builder didn't understand that the fan would be sucking(or blowing) air into the chamber.(And consequently would be creating high and low pressures within)

The net result was that the walls were sucked inwards and the walls needed rebuilding within a week of use. A very costly exercise.

tell the builder what forces the space will encounter.

Also are you near heavy traffic. A sensitive acoustic chamber can pick up traffic noise unless the whole structure is suitably isolated.

Friar Tuck of Sherwood

 

[aathi1]

Hi Guys,

Well I would rather to recommend to findout all the details before make decission to build chamber. Before you meet the vendor or manufacture you need browse the standard ECMA74.

In the standard tells about the following chambers:

Anechoic Chamber
Semi Anechoic Chamber
Reverbation Chamber
Mini-Reverbation Chamber

And also make sure what you need to be tested in the chamber and follow checklist items below.

1. Background Noise of the chamber expectation
2. Type of Microphone
3. Enclosure (if you need lower background noise than you need enclousure)
4. Equipment or Tester (B&K, dB Sonic, Head Acoustic and others)
5. Vibrations

Regards,
Balan.G

 

[GregLocock]

I strongly recommend that you do not consider reverberant rooms.

from a practical point of view I think you'll find a SAC is the way to go.

Cheers

Greg Locock

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

 

[JCRampone]

I would be able to help you with the design and construction of the anechoic chamber your sister company is interested in purchasing.

Please respond and let me know if you would be interested in my services.

 

[Rob45]

If you're in the U.S., I can recommend Eckel as a source for an anechoic chamber.
They have a great deal of experience in this.

(Tell Alan I sent you!)

 

[aathi1]

Yes, I strongly recomend Eckel is good source to discuss for anechoic chamber. We just finalized with Eckel to build another anechoic chamber in Asia manufacturing plant.

________________________________________

Regards,

Balan.G