Detecting of sound...

[eLGin]

Hi i am currently working on a project where i have to make a circuit which can detect sound.most preferably is used under a class room which i can detect the noise levels and send the signals into 8051 micro controller and display a message "the noise level is too high" onto lcd display.
I wonder if any peeps out there who can help me with my circuit?

Thanks

 

[Nigel Goodwin]

You might try looking at http://www.discovercircuits.com/V/vu-meter.htm which has a selection of sound level meters.

 

[zachtheterrible]

HAAA HAAAA :lol: . thats perdy funny. u wanna make a sign that lights up when someone in ur classroom is making 2 much noise? good idea, but u have 2 remember that chairs scraping across the floor, dropping back packs, etc will set off the sign. An idea might be to make it so that the sign will only light up when the noise is too loud for 2 seconds or so, that way scraping chairs n stuff wont set it off. Wut grade do u teach?

 

[eLGin]

hMm i i only have a rough idea.i just mainly think that i only need to detect sounds made by people.Regarding about the chairs sounds,i just imagine myself having a classroom whereby chairs are screwed to the ground.Some sort of a small lecture mini room.

Human voice have the range below 3khz.I just mainly have to build a circuit which the noise is only too loud.hMm i wonder if anyone is good in this?

I guess my project is almost similar to a P.A system;microphone,preamplifier...etc.