Silence Detector Circuit

[onlyelectronics]

please guide me to make a silence detectr circuit which turns ON the LED after 5 seconds of silence.

 

[Raven Luni]

Is this a homework question?

The basic principles are as follows:
- Detect sound level for example a rectified signal from a microphone (its a level so only look at a single polarity)
- Use a comparator or something similar to set your threshhold
- Send the output to a monostable 555 or similar set for 5 seconds
- Invert the output from the 555 to light the LED (so it goes off when triggered and lights again after it times out from inactivity)