Hi, I was wondering if anybody knows if you can use software to emulate a Sound Level Meter using a soundcard and speakers. I would like to be able measure the db level of my home stereo. Thanks.

I have been using this. He has several different VU styles.

http://www.darkwood.demon.co.uk/PC/meter.html

Without a calibrated microphone and input stage, the results will be meaningless.

Sorry!

Cheers,
David.

Thanks for the replies.

I have a Rode NT3 mic rated as:-

Sensitivity: -39dB re 1 volt/pascal (12mV
@ 94dB SPL) +/- 2dB

Does this information help calibrate for an accurate result?
Would that mean that without pre amplification the recording is -39 db below the level of the source?

Thanks.

I'm just curious, I guess, but why do you want to do this? It's an interesting idea, I admit, but really, an SPM only costs like $15-20 at Radio Shack.

>I would like to be able measure the db level of my home stereo.

And what does that mean, exactly? The dB is dependant on how loud you turn up the volume, you know. The reason you need an SPM is to calibrate the amp to equalize the level of volume coming from different speakers.

Ohhhhhh.....A sound level meter. I thought you wanted to measure input levels to your PC. I misunderstood. You want to tell people how loud your stereo is

I don't care about others views of my stereo. I was interested as I am undergoing hearing tests to measure possible damage done to my ears. I would like to be able to have an independent, scientific measurement of typical audio levels I am exposed to (I work in multimedia which includes some sound production).

My motives are to LIMITED any further damage not the petty, childish crap that has been suggested.

P.S. The theoretic db resolution of a CD should not be confused with the real world db that are heard due to the amp and speakers (they are two completely different uses of db).

Ohhhhhh... Sorry, I misunderstood the original post then.

You won't be able to afford anything that would provide "independent, scientific" measurement. Making accurate, relelvant measurements of sound pressure level is extraordinarily difficult.

If you had the technical expertise to make the measurement you could probably rent the equipment from one of the nationwide scientific instrument rental agencies, but judging from your question you'd probably be better off hiring a professional to come in and measure the sound levels for you.

-- Rick

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Moderation: removed long off-topic signature.

Your best best would be to purchase a radio shack sound level meter rather than trying to calibrate the PC, too little information is know about the input impedance and sensitivity of your sound card input to figure an accurate result.

Even so, these SPL levels you obtain, scientifically, would be more or less meaningless. Both SPL and frequency factor into hearing damage, ie you are much more tolerant of lengthly exposure to a 30 hz sine wave at 110db then you are a 2000 Hz wave at the same sound pressure level.

There is, however, a process devised to determine the cummalative effect of workplace noise...but I can't seem to find my noise textbook right now to explain it.

I goofed the answer above a little... as long as the meauring device you are using is 'A' weighted, it will compensate for the effect of frequency.

The radio shack meter is capable of applying 'A' weighting and gives an average SPL level for you, I would highly recommend going this route.

You would need to measure the SPL level at intervals during the day to get an average exposure level. You use the following formula to do this:

Daily exposure = C1/T1 + C2/T2 + C3/T3 + .... Cn/Tn

where Cn = Time of exposure at specified A weighted SPL level
Tn= Total time of exposure permitted at specified A weighed SPL level (as determined by the Ocupational Health and Safety act.)

also, Tn = 16 / (2^((dBA-85)/5)) where dBA = A weighted SPL

The answer will be in a decimal percentage.

This is your original post:

"I would like to be able measure the db level of my home stereo. Thanks."

I'm not sure how anyone one would confuse that with wanting to see how loud your stereo is

The implication being that he wants to brag about his setup.

Actually, I was somewhat joking when I first suggested that, and it was taken a bit too seriously.