Best way to to monitor sound level to catch intruder?

Hello I'm designing sound triggered alarm for my home, have general question, what is the best way to listen for sound reaching loudness threshold.

  1. Measure difference between highest and lower readout on analog pin over short time frame and if it reaches some certain threshold then alarm?

  2. Just constantly listen for voltage on analog pin and if it reaches some certain value then trigger alarm?

I'd expect false alarms from outside noises... A truck driving by, thunder, an airplane overhead, a dog barking...

I've heard of detectors for detecting the sound of breaking glass (maybe just for car alarms) but I don't know how reliable they are. Most alarm systems use motion detectors and/or magnetic switches on doors & windows.

  1. Measure difference between highest and lower readout on analog pin over short time frame and if it reaches some certain threshold then alarm?

I don't think the lower reading will give you any useful information. And, if you're reading the "waveform" (such as the output from a microphone & preamp), the waveform crosses-through zero twice per cycle, so the minimum is of no use.

Just constantly listen for voltage on analog pin and if it reaches some certain value then trigger alarm?

I think you'll have to experiment to see what kind of readings/data you get when there's nobody home and when people are present.

Maybe a certain number of peaks above a threshold over a certain period of time. But, I think you'll have to look at/analyze the data to figure what will work.

...My alarm system, which I installed but did not build, has motion detectors, and sensors on my doors, but no sensors on the windows. It's also got blinking LEDs and stickers at the doors to let potential burglars know I have an alarm. So far, no burglaries or attempted burglaries. But, I have had a few false alarms.... It's usually a door that's not latched (and the wind blows it open enough to trigger the alarm) and maybe something's triggered the motion detector a couple of times.