Child Crying Control

Child Crying Control using open source tools.


How to get your neighbors annoying constantly crying child to shup up using simple automation.

(disclaimer, I have actually not used this system as I am way too nice a person.
The whole text is written in dispair as my neighbors child has a nasty habbit of crying furiously through most of the night, and the parents fails to control it.
I have tested the technical aspects of the system described below and they seem to work well.
Still, hower, this is rather drastic measures and  talking the matter over with the parents will surely give better results. After all. Even parents must acknowledge that other people exists outside their baby-bubble)

In this experiment I will be using open source tools. I do not like using Window$ very much and has hence found some programs that runs on Debian Linux. You can surely find similar for Window$.

Anyway... Lets get started....


  • Smaller Children and babies are crying at a frequency at 1000-5000 Hz, centered at 3500 Hz. This is also the frequency at which adults are the most sensitive, making it even more annoying.
  • Babies and small children has much better hearing in the higher frequencies than adults. Ideal hearing goes up above 20kHz, but degrades aldready from the the 8th living year. As a result, most children and a few adults can still hear tones aproaching/surpassing the 20kHz
  • Most small children learns well by repetition.


shock collarShock Collar for Dogs

In dog training it is possible to get electric collars in order to give the dog a gentle zap whenever
it oversteps its bounds. After a short while the dog will learn not to enact in a specific activity.
It is quite likely that this theory can be used on humans as well.
As we cannot very well zap the children, we can nudge them in the right direction using a high annoying sound
every time they overstep their bounds.

In short: Detect crying and respond with a powerfull blast of sound in a frequency area that only they can hear.

The tools

  1. A computer running Debian, Ubuntu, Xubuntu or another derivative - or windows if you do not mind searching for other
    audio triggerConfiguring Audiotrigger
    programs that will run under this OS.
  2. Audacity. An open source tool to manipulate sound. It has an buildin tone generator and can generate a tone high enough that only small children will be able to hear it. Get the program HERE. (Also exists for windows)
  3. AudioTrigger. An open source tool designed to detect sounds within specific parameters and run a program as response. While it is not perfect and does detect a "loud high pitched sound" instead of "crying", it is good enough for prototyping If you need better control, do some MatLab ccripting instead. Get AudioTrigger HERE (The program is made for Debian and distributed in .deb format. If you use an alternative OS, you can probably find something else.
  4. Mpg123, A command line player that can play mp3 files. Install it by typing "sudo apt-get install mpg123". It is run with the command mpg123 fairness.mp3. If you were on Windows, you could use Windows Media Player that is part of Windows. It can be run from command line like this "c:\wmplayer.exe fairness.mp3"
  5. A highend amplifier. Most amplifiers does not do well in the edge of the audible spectrum. You might need a highend amplifier to reach 20KHz
  6. A pair of good speakers. As with amplifiers, cheaper speakers are centered around the frequencies that are used the most. Speakers designed for Jazz or Classical music will do fine.
  7. A Microphone. Luckily you do not need an expencive one. Childrens crying are smack in the middle of the recordable spectrum, and you can probably detect it even from the buildin mic on a laptop.

The doing

Well, from here it is fairly straight forward:

speakerwallYou will need plenty of amplification
  • Use Audacity to create a highpitched sound only the children can hear. Personally I have quite good hearing, so I had to go way over the normal 20kHz. The specific frequency is, however, not that important just make sure that it is just above what your own hearing accepts.
  • Setup AudioTrigger to play the sound whenever it detects crying
  • Make sure the amplifier is turned well up. Higher frequencies do not penetrate walls well.


While this should work, it is utter bullshit and should not be nessesary. It is the kind of thing you would only ever do if your sanity was in threatened (which repeated sleepless nights will do).
Parents should take care of their kids - They chosed to have them, not the peaceloving neighbor.
If parents cannot themselves take care of the kids, they should seek help.