I've always been very annoyed by those regular single beeps that smoke detectors start doing increasingly often as the batteries start to run out, to warn the user to replace the batteries.

Lately, I've been observing how a bunch of kids seem to sit in a room and just ignore those beeps completely, even after I point it out and ask them to really listen. They can't hear them. I seriously believe that they just don't physically hear them. Kind of like those dog whistles.

Is this backed up by science? Do kids under a certain age literally not hear those "low battery" warning beeps? Is this maybe per design, even? If so, why? Isn't it important that as many humans as possible hear this so that they replace the old batteries with new ASAP?

It's really frustrating to me when they don't even hear it, but I hear it very well.

I already asked this question a few days ago in "Biology", but it was "off-topic".

  • 1
    $\begingroup$ I doubt that they can not physically hear the beeps, unless for some reason they all have hearing defects. But under "a certain age" they will have no idea of the significance of the beeps, so it is quite likely their brains will just tune them out in the same way that they ignore other random noise. Having once spent a few weeks (as a patient) in a hospital environment where warning beeps of various types were going off regularly throughout the day and night, after a few days I didn't "hear" them in the sense of "react to them" most of the time, even though my hearing is normal. $\endgroup$
    – alephzero
    Commented Jan 23, 2020 at 1:13

1 Answer 1


Unless they have hearing loss, young people tend to be able to hear a larger range of sound frequencies than older people, particularly higher frequencies:

Some security companies recently began manufacturing machines designed to emit an annoying sound that prevents teenagers from loitering outside stores and shops. Teens are effectively driven away, but many adults can’t hear this sound at all! Things got even more interesting when some kids realized they could turn this technology on their elders by making the sound into a ringtone. Students with the ringtone can receive text message notifications during class without many teachers or administrators suspecting a thing.


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