Ambient noise wanted

[vincei]

I apologize for being such a newbie, but I can't find information anywhere on what I am trying to do.

I'd like to record ambient noise in a room, with an accurate measurement of sound levels (dB). The idea is to continuously measure sound coming through windows, through walls, at different parts of the room.

Then I will dissect the noise into frequency bands and simulate the effect of various noise cancellation technologies (windows, dampeners, etc.).

I will be using a standard laptop PC to collect all the data.
Ideally, I would be able to collect from multiple sources simultaneously.

Does anyone have any suggestions on how to proceed (without resorting to overkill)?

Thanks,
vince

 

[RAK]

Why not just get an SPL meter? They normally (if not always) have an audio ouput, so you can hook it up to your laptop to record. There are a wide ranges of prices/quality/design (analog/digital), but for example, here's one for $30 from BSW. It has a mono RCA output, so you can just get an RCA -> 1/8" cable (or connector) and hook it directly to your sound card's line input.
They're usually stand mountable as well.

http://www.bswusa.com/proditem.asp?item=SLM100

 

[apl]

The idea is to continuously measure sound coming through windows, through walls, at different parts of the room.

Then I will dissect the noise into frequency bands and simulate the effect of various noise cancellation technologies (windows, dampeners, etc.).

That is a very highly technical measurement involving phase matched mics and looking at the imaginary part of the crosspower spectrum.

 

[vincei]

Thanks for your responses

I looked at SPL meters, but I was hoping to avoid the frequency weighting bias. I would like to get a setup with relatively flat frequency response, so I could do my own spectrum analysis. Audacity seems to have most of the functionality I need.

The basic setup seems to be microphone and preamplifier. I'm not sure whether a mixer is the way to go here or not.

Any suggestions?

 

[apl]

I looked at SPL meters, but I was hoping to avoid the frequency weighting bias. I would like to get a setup with relatively flat frequency response, so I could do my own spectrum analysis. Audacity seems to have most of the functionality I need.

The basic setup seems to be microphone and preamplifier. I'm not sure whether a mixer is the way to go here or not.

Any suggestions?

You need an acoustic intensity probe, an spectrum analyzer, and the related software. Budget around $30k, if you really want to measure sound coming in from different parts of the room.

 

[RAK]

Unless you get microphones specifically designed for the type of testing you're talking about, you still could be dealing with a "weighting" bias in the microphone, same as with a SPL meter. Sometimes I get A and C weighting confused, but one of them is relatively flat (at least more flat than the other )

Now here's a mic from Behringer for only $49.00 from Zzounds. Freq. Response is 20 Hz - 30 kHz. But I'd be suspicious of that, for a few reasons.

http://www.zzounds.com/a--2676837/item--BEHECM8000

For contrast, here's a line of reference mics from Earthworks, the cheapest with a Freq. Repsonse of 9 Hz to 30 kHz. Of course a Froogle search shows it goes for around $700. Probably good though.

http://www.earthworksaudio.com/25.html

Keep in mind, even if you have a microphone that can measure up to 30 kHz, you're still limited to the freq. response of your pre-amp.

Earthworks has a single channel pre-amp with freq. response up to 200 kHz going for about $1,200

 

[vincei]

well...

Thanks for both of your responses.

I'm not as concerned with where sound coming into the room as much as perceived sound at different points in the room.

Also, I'm confident a decent A/D sound card and computer should satisfy my spectrum analysis needs.

So I guess the question boils down to whether to go with a full blown condenser mic + preamp or the SPL meter.

I found a web site relating to sound measurement rather than recording, so maybe that's the place to go.

Thanks again,
Vince