Author Options:

Automatic baby cry detection Answered

A friend of mine asked me today if I could help him construct an automatic crib for his newborn child. He wants to make a crib that automatically starts moving from side to side when crying sounds are detected. How do I make something to detect crying?! Where do I even start on this one.. ? :)


How about "get yer arse up and take care of your child"?

Um... I meant that in a nice way. I have a young one and I feel your pain. For serious bodging together, find any sound-activated toy (there were quite a few holloween decorations that had sound activated bits this year) and have it trigger a rocking device as suggested by kiteman. My solution? I put a modified a canine training collar for my wifes' ankle. Whenever the noise from the baby started to bother me, a quick push on the remote trigger would get her moving.

. I don't think you'll need to get as complicated as Goodhart is saying. You should be able to trigger on any "loud" sound as the baby will probably be in a relatively quiet room.

Yeah, you're probably right.....I tend to over do things at times ;-)

You can get baby monitors that flash a row of LEDs - the louder the cry, the more LEDs light up.

You could open one of these up and use the output to one of the LEDs to trigger a rocking device - just select the appropriate LED to match the amount of crying that would normally make you get up and rock the crib.

The actual rocking device should be fairly simple as well - there are commercial versions available that consist of motors with off-set masses on their shafts, effectively large, slow pager motors. I think some of them even have timers, so maybe all you need to do is connect the LED supply to a solenoid, and replace the on-switch of the rocker with a reed-switch.

And then, maybe a timer that would sound a quiet alarm in your room in the event that the rocking didn't accomplish it's said end (in the event something else is wrong in other words).

If you're working it via a baby monitor, you'd be able to hear what's going on anyway.

From experience with an alarm clock, if a person ignores a sound often enough, they may eventually not hear it at all. This is the reason I never use the snooze alarm anymore. I had to move my alarm clock clear across the room when younger, just to get me awake enough to go shut it off, rather then sleep through it. After using that snooze button enough times, I eventually just didn't wake to the noise at all.

Hehe, I have the same problem. Some times the alarm clock can ring for a full hour and give up without me even noticing. It's best to use a cellphone and change the sound from time to time :)

Well, it would wake me, but then I would shut it off without waking fully. That was the reason for the moving it across the room.....I had to walk barefooted across the hardwood floor to turn it off......I was awake by then :-)

Hmm, all this talk about the failure of alarm clocks to wake people up properly got me thinking.. I've been thinking about making a "room integrated" alarm clock. A system that integrates with the stereo, lights, maybe a vibrator in the bed... Perhaps the most effective thing would be to sew in fine strands of wire or other electrically conductive material in the bedsheets, and connect them to something that delivers a small electrical shock :) Or better yet. Put an hydraulic ram under one side of the bed, and have the bed tilt slowly up to 90 degrees when the clock rings This would be a fun instructable ;)

Perhaps the most effective thing would be to sew in fine strands of wire or other electrically conductive material in the bedsheets, and connect them to something that delivers a small electrical shock :)

That might be trickier then you think. And not just in regulating the shock to be "non-lethal" but still effect in waking, but actually administering a "shock" at both low current and without the person being substantially grounded.

Motor controlled bucket of water suspended over the bed then.. ;)


Gives a whole new meaning to "wetting the bed:, Eh ?

um, just call me a "wet blanket" LOL


10 years ago

Babies, when they cry, do so loudly, and if they aren't crying loudly then they don't deserved to be rocked. So couldn't you forget about frequency, and simply use volume?

Well, my first thought was that, since babies are not all "tuned" the same *chuckle* some are louder then others. But yeah, if one was going to do this, they could tune it to their own baby's volume I suppose.

That would have to depend in the frequency and volume "emitted" by each individual baby, I would think. You may need to either record (and later measure) or simply measure as it happens, the crying and find the range of frequency you are looking for. The problem will then occur that this will not always work. I mean, it may "rock the boat" every time, but that is no guarantee that the crying will be shushed. :-) A wet, "dirty", or hungry baby will need attending to regardless.