Practicality of generating electricity from ambient noise
How about some numbers?

0.775 volts into 600 ohms is one milliwatt.
A blue LED needs 3 volts and 20 milliamperes.  That's 60 milliwatts.
If you collect energy at 1 milliwatt for 60 seconds then you will have enough energy to light that blue LED for one second.
Typical microphone output levels are about 1/1000 of one milliwatt.
It would take about 60000 seconds (nearly 17 hours) to collect enough energy to light the LED for one second.

Keep in mind that all of those numbers are optimistic estimates and that they assume that you can store all collected energy without losses and that you can convert voltages without loss.
There is no way that you can collect a useful amount of energy with a normal microphone in a normal home.