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Comment by JoeAltmaier | Hacker News Reader

Also, we hear using the cochlea, a spiral sense organ that sorts sound by frequency. In children the whole thing is much smaller. So they hear much-smaller wavelengths of sound which means higher-pitched sound. As we grow so does the cochlea so we hear lower and lower sounds and lose the sensitivity to the highest-pitched ones?

I'm guessing that hair dryers have a scream in the upper register that adults don't normally hear.

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That's very possible indeed. I remember when I was a kid my grandparent's tube TV was making a high-pitched sound that was figuratively driving me insane (maybe generated from the HSYNC frequency, now that I think about it). I couldn't understand how they could bear it but of course when I told them they didn't get it because it was probably way outside of their hearing range. I'm fairly sure that now that I'm in my 30s I couldn't hear it either.

Typically a high-pitched whine from a CRT is from the flyback transformer. I found, when I was a kid, that sometimes a well-placed whack on the CRT's cabinet could temporarily fix the problem.

Nowadays, I have no idea if I can hear that whine anymore or not, as CRTs are quite uncommon. Probably not. Much for the better, as it used to give me headaches.

15Khz colorburst whine. Its amusing how many audio recordings even today show a notch filter used at that frequency, years after there were no CRTs anywhere in the recording process.

There are recordings that really should have had it!

https://open.spotify.com/track/3B4q6KbHbGV51HO3GznBFF?si=Fgy...

https://open.spotify.com/track/6PsISpFaCEKwysPfwO9SfC?si=NQa...

(Or if these whines aren't CRT related, I'd be curious to learn the source).

Flyback, not colorburst. Monochrome sets should exhibit the whine as well.

You might still be able to hear it.

https://youtu.be/8XzNh5U8Jzw

https://youtu.be/rkEQ0b35nzw

https://en.wikipedia.org/wiki/The_Mosquito

> The Mosquito or Mosquito alarm is a hand wound machine used to deter loitering by young people by emitting sound at high frequency, in some versions so it can be heard mostly by younger people.

> The sound was made into a mobile phone ringtone, which could not be heard by teachers if the phone rang during a class.

At 35, I'm still deeply bothered by that sound. Slightly related but in a lot of parts of Ginza in Tokyo, they use a similar sound for repelling rats that I find extremely uncomfortable...

I have read this many times online and i think i must be the only one who for some reason liked that CRT sound :-P

Though it might be that since i really loved computers, i associated it with computers and liked it via association.

I was quite surprised as a young adult when one of my ears couldn't hear cricket chirps anymore. If I laid with one ear against the pillow I could hear them, but if I turned over it was silent. A hearing test confirmed that one ear was deficient.

I'm 39 and I can still hear 15kHz flyback. Not as loudly as I used to be able to, but it's still there.

This is not true.

The dimensions of the cochlea are basically fixed at the time of birth. As the dimensions of the cochlea are the main contributing factor in what tones are able to be heard, the tonal bandwidths are then set at birth as well (minus hearing loss due to damage as we age). If you are interested in how sound is interperted by the brain, be aware that it is not a straightforward process and takes a bit of research. Still, the cochlea is essentially fixed at the time of birth.

More on how the dimensions of the cochlea determine tonal bandwidths: https://en.wikipedia.org/wiki/Hair_cell

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970226/

[1] http://www.ajnr.org/content/ajnr/early/2011/09/29/ajnr.A2713...

It's not due to cochlear size, we lose sensitivity to high frequencies because the hair cells slowly degenerate with age.

It's not only due to size...

Does that mean that children also don’t hear deep bass? Is it commonly accepted that young children don’t enjoy the sort of music (e.g. dubstep, drum-and-bass) that employs near-infrasonic notes?

Even as adults, you feel anything below 45hz or so more than you hear it. I am confident that children feel too. But the bass heavy club music ypu describe has an adult cultural element, otherwise missing from most music.

An other thing to consider with deep bass is that, at least in concert/club conditions, you feel the bass with your body on top of hearing it. So even if your ear struggles to capture those low frequencies you'll still experience them somewhat.

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