I am working on a mini project for a school who want to detect sound levels in the classroom and been going around in circles for a few weeks. There want to measure sound levels but ranging from very low sound i.e. chair moving, door opening to levels of talking within the classroom.

I appreciate to get an accuracy levels a number of microphones locate in different parts of the classroom would need to be provide. But, just to be able to monitor sounds levels I would like to build a simple sound meter.

I have used many of the Arduino type microphones and built pre-amps using lm358, 386 and BC548 circuits but none of them provide the response I am looking for. Many of the circuits seem to be very noisy and not seeing the response which I am looking for.

Audio analogue electronics is not area of expertise and looking for some ideas on suitable circuit and design.

 

Hello,

Have a look at the following project at ESP:
http://sound.westhost.com/project93.htm

Bertus

 

Measuring relative levels of sounds would be much easier (and cheaper) than measuring absolute levels. Which type of measurement do you have in mind?

 

When I was into studio recording I used a surface pressure microphone. You mount it on any large flat wall and it detects the sound pressure when sounds hit the wall.

It's ideal for detecting all the sounds in a room, as an alternative to having lots of microphones.

http://www.mediacollege.com/audio/microphones/pzm.html