simple noise meter

labview1958 · Post by **labview1958** » Thu May 11, 2006 2:37 am

I want to make a simple noise meter. The purpose is to detect the noise level outside my house. I want to measure the noise level. I am looking for a sound sensor plugged to a chip that converts sound to voltage and conected t a voltmeter. Any ideas?

JPKNHTP · Post by **JPKNHTP** » Thu May 11, 2006 2:43 am

-JPKNHTP

labview1958 · Post by **labview1958** » Thu May 11, 2006 8:35 am

How do I convert the noise from the trafic in front of my house to a voltage? Do I use the microphone?

philba · Post by **philba** » Thu May 11, 2006 9:11 am

I suggest that you buy a logging sound level meter. I base this on the fact that you wil need to calibrate the device and your obvious skill level. extech makes a fairly nice one with an rs232 interface for about $250.

labview1958 · Post by **labview1958** » Thu May 11, 2006 9:40 am

How to make a simple one?

dacflyer · Post by **dacflyer** » Thu May 11, 2006 11:25 am

the VU circuit above will work just fine with a dynamic microphone
or a old headphone speaker from a old walkman or such.. then you just adjust it to your needs. hope this helps ya ..

i also think you might be able to do it with a headphone speaker, dioad and a cap and a meter,,you will need also a good pot to adjust the sensitivity, so that you do not slam the meter , this is about as simple as i can think of,, will not be super accurate, but it should do you for you..

labview1958 · Post by **labview1958** » Thu May 11, 2006 5:23 pm

Does the microphone picks up all the noise as a human ear?

JPKNHTP · Post by **JPKNHTP** » Thu May 11, 2006 5:28 pm

-JPKNHTP

dacflyer · Post by **dacflyer** » Thu May 11, 2006 9:06 pm

ya and some times a bit more...

the electric mics are better for hi frequencys,
and the dynamic (dynamic?) ones are better for low frequencys

philba · Post by **philba** » Thu May 11, 2006 9:38 pm

actually, it is much more complex than that. every mike has a characteristic frequency response curve. the data sheet for the mike should show it. it may roll off at a few kilohertz or may well go quite high. it may also not be very sensitive at the really low end.

In addition, microphones are not perfectly unidirectional. They will have different response depending on where the sound is coming from. some are better than others but even "omnidirectional" mikes aren't perfect.

dyarker · Post by **dyarker** » Thu May 11, 2006 9:53 pm

I re-suggest that you buy a logging sound level meter.

philba · Post by **philba** » Fri May 12, 2006 8:27 am

dyarker wrote:I re-suggest that you buy a logging sound level meter.

JPKNHTP · Post by **JPKNHTP** » Sun May 14, 2006 3:00 am

-JPKNHTP

grant fair · Post by **grant fair** » Tue May 16, 2006 12:00 pm

The circuit in the last post will work, just put your plus voltmeter lead at the "sig" output in the top schematic, and the negative lead attached to the ground of that circuit. The LED circuit on the bottom is just a substitute for a voltmeter so it can be omitted.

If you want to buy one, Radio Shack has sound level meters for under $50. A proper sound level meter contains some filtering so that the meaurements correspond to how the ear perceives loudness. (Google Fletcher-Munson curves for more info). At low levels, the ear does not hear low frequencies as well as it does at higher volume levels, so this may not be needed in your application.

Do you need to calibrate it? Are you trying to get something done to reduce the noise?

Grant

labview1958 · Post by **labview1958** » Wed May 17, 2006 5:30 am

Where can I buy a ready made sound meter that mesures sound as heard by the human ear. I am interested in reducing human noise. Noise caused by people talking loudly. Is there a way to reduce such noise by some scientific method. If people knew their noise level, then maybe they would shut up.

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