Detect decibel from microphone

Hey guys,

I know I've been gone for a while because I've been thinking hard about this project I am beginning to do! What this project contains is a microphone - an op amp to boost the audio power then I would like this to be plugged into the ADC input for analysis. For instance, if the Arduino Uno detects a decibel of -60 to -80 decibel then it would trigger a LED to indicate an "abnormality". Why between -80 to -60? Electronic Voice Phenomenon usually occur at that lowest range. Would it be much wiser if I was just used a comparator instead? Any input would be most appreciated!


An opamp is a good way to amplify the microphone output. If you start with a small electret condenser type microphone, a single opamp could amplify low level sound into the 0 to 5V you want for the Arduino input. Make the gain adjustable.

On the http://ArduinoInfo.Info WIKI see: and scroll down to NE5532. Follow links to circuits etc..

Electronic Voice Phenomenon usually occur

??? What is that? Have a link on wiki?

Thanks Terry for the input! Yesterday, I purchased the LT1630 from digikey and other components for the equipment. I am unable to show any more details about the device because once the device is done prototyping and field-tested - then it will a finalized product to market to other paranormal investigators.

I'll look at the values that I'll get from arduino soon but what I can say is that I stripped the plug of a headphones; attached it to the Analog Input 0 then plugged the jack into my speakers. Played with the volume a bit while looking at the serial monitor in the Arduino IDE.

My mind is a bit scattered about but once I get the electret microphone from digikey then I'll analyze the audio coming in from the LT16430 Op Amp.