I am not sure if here is the right place to ask my question. But I will ask.

I want to build some kind of sound detector circuit to prevent sleeping baby from disturbances. But, it should detect only the disturbing sounds. As it is related with the human perception I know there is no exact answer.

The question I want to ask is, which property of sound disturbs us? What type of sound can wake us up from sleeping. Do, I need to detect the frequency regions or the volume it self. If I am not wrong, the volume is proportional to the voltage detected by the mic. So, the voltage level is enough, or do I need to filter the sound based on the frequency. If I need filtering, which frequency region do I need to pass to detect?

Thanks for reading.

2 Answers 2


Change is typically "disturbing". A sharp change of amplitude (a crash, a scream, an explosive sound, etc.) Or even sudden quiet after moderate but steady background noise will disturb some people. So a circuit that detects any sharp change (up or down) in sound amplitude. That would be my primary focus for detection of "disturbing sound".

Of course, even if you could detect "disturbing sounds" it is not clear how you could "prevent sleeping baby from disturbances". Both the detection/reaction time AND whatever transient method of "prevention" seem problematic to creating something practical for the Real World.

  • Actually, the circuit will work only for detection, not prevention. Detected disturbance will trigger some visual alerts to take attention of the parents in order to clear that disturbance. That disturbance may be the loud conversation, high volume tv etc. So, your suggestion is, the measure of amplitude should be fine for that? But what threshold values should I take a look for. How much sound is considered as disturbing sound?
    – freezer
    Commented Apr 20, 2016 at 8:47
  • Nice answer. A persistant or repeating sound can be disturbing too. But babies can sometimes sleep through thunder, and be woken by a quiet footstep another time. I don't think this idea is practical either. The last thing parents want to buy is another thing that wakes them every five minutes!
    – n00dles
    Commented Apr 21, 2016 at 14:20
  • Hi, this won't be a product to be sold. I am building it for a friend of mine as a present. It doesn't need to be complete professional and it should work a bit for intended way. :)
    – freezer
    Commented Apr 22, 2016 at 9:37

Since change is what is typically disturbing, many parents employ a source of white noise in the nursery to raise the noise floor, thus lowering the change swings in ambient or transient sounds. A fan is common, or an FM radio tuned between stations, or an overpriced first-world consumer device that produces digitally synthesized simulations of surf or gentle breezes.

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