Turning on lights in response to noise

Here’s my real scenario: weekend place somewhere farther our, solid internet connection, have a SmartThings hub that I use to control heat and other stuff. There is one neighbor relatively close, meaning also far out, and that neighbor told me the other day that at 3:00 AM somebody pulled up in a car and laid on the horn for half a minute, then waited. When she turned on her light, the car took off.

Hmmmm. Somebody was checking to see whether anybody was home, and the way they did that was by making noise and checking whether something happened. If you walk up to a place and the lights go on, well, that’s a motion detector, doesn’t tell you anything if somebody’s in or not. But if you make noise in the middle of the night and there’s no reaction, quite likely there’s nobody there.

So what I’d like to do is put a noise detector there, and if there’s a burst of noise (and nobody’s home), wait a couple of seconds, then turn on bedroom lights, then turn on outside lights. Problem is that I don’t see a noise sensor that would figure out whether there’s noise (yes, a microphone will give me plenty of information, but not condensed down to what I’d like, some sort or signal I could use to trigger the sequence of lightups (possibly including cameras, come to think of it). I see the “Quirky Spotter Uniq” which appears to be in limbo and… nothing else. Is there a device out there that would detect something like a honking horn ? Thanks for any pointers.



I would check this out if you’re interested in getting your hands dirty.


I was going to share the same thing.

You’d just need to set it up to sense sound over a period of 10 seconds or something to get less false positives.

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I think it very unlikely that a burglar is going to rely on leaning on a car horn for 30 seconds as a means of casing potential targets. They’re going to wake up the neighbors and draw attention to themselves. Not a good business model for a sneak thief. :wink:

Most likely it was some drunk teen who had the wrong house, and took off when they realized their error.

That said…

The reason it’s so hard to find general audio sensors for security purposes is because of the number of false alarms. We’ll see if Quirky Uniq actually ends up working for audio.

There are some baby monitors that are sound based (although fewer every year, most now use motion), but again, it’s unlikely to be precise enough once the sound is " somewhere outside."

If you are the target of a stalker who’s after you personally, the lights coming on won’t deter them.

If it’s just a burglar looking for a target of opportunity, motion detection in a zone pattern or IR beams should be sufficient. After all, whether someone’s home or not, where there’s one automated system there are likely to be others.

The Clapper that’s been suggested is worth considering, but again, really hard to adjust appropriately to detect what you actually want to detect. (One word: thunderstorm.)

On the other hand, your suggested result event, lights turning on, is pretty benign, so maybe you won’t care about the false alarms.

But my guess is the original horn event didn’t represent a potential thief to begin with, if that’s of any comfort.

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Just read the horn part… Good luck getting a device to discern that… Not impossible but it will be difficult.

If your internet is good, then I think it’s absolutely worth listening for a loud noise, then turn on a light or two, and notify remotely.

Cameras should be on all the time and saving to cloud anyway.

It’s worth trying, but my guess is the lights will end up coming on almost every night. And what will turn them off again?

(Also the whole issue of testing, but we’ll leave that aside.)

The human brain sorts noises into categories far more sophisticated than their decibel level. We’ll say a distant noise is “very loud” even when it’s actually quieter than, say, the refrigerator compressor, because the “very loud” noise has contextual information for us. IF we can hear it when it’s outside and we’re inside, we “know” it’s very loud even though, measured at the point where we hear it, it actually isn’t.

We also overweight the importance of anything in the “crying baby range” (that’s a thing), which is how many sirens and horns work.

We also judge noises of extended duration or in repeating patterns as louder than they actually are.

Dogs do a lot of the same stuff, btw, which is why we still use them for perimeter detection. They’re smarter than a decibel measurement. :dog:

There’s no harm in trying to see if it works at a particular location. I’m just saying there’s a reason these devices aren’t commonly used, so don’t over invest in anything you can’t return after a couple of weeks.


Nah, this is out in the boonies. My neighbors and my house are the only ones within earshot. I thought about just putting up a sign saying something to the extent of “heavily automated house, burglarize at your own risk”, possibly in connection with a motion detector that is turned on when we’re not there…

Yeah, the noise level detection threshold is going to be interesting to figure out. Good thing this place is in a really quiet area, so I don’t have to distinguish sounds.

What will turn them off again ? Hopefully a smart app… Currently I am turning the lights on and off on a schedule, may have to build a better smart app that does so randomly - while we’re not there…

There are some community created apps that do the random light pattern thing. Vacation Light Director is one. :blush: Worth a look:


Not sure if “quiet neighborhood” also means rural, but in my neighborhood calling coyotes set off baby monitors that are triggered by sound. So do yowling cats. Noise detection is always interesting. :wink:

Awesome - looks like precisely what I was trying to achieve, will give that a shot. Thanks.

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