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Comment by xzel | Hacker News Reader

I’m a bit older than average and these types of things and noises drive me crazy. I can’t even be near some old CRT screens due to the pitch they emit (especially bad with old CCTV monitors).

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I may have lost a little at the high end or electronics have gotten better filters, but I used to grumpily stomp into the next room to turn off the tv or the VCR because it was bugging me.

There was a story a few years back about stores getting rid of young loiterers by playing these tones, then later on kids setting ringtones or alerts on their phones so that the teacher wouldn’t get mad that their phones were on. Guess what? A lot of surprised 15 year olds had their phones confiscated by disgruntled 40 year old teachers who could damn well hear the ringtones.

The TV noise you used to hear is gone because CRTs are gone-- it comes from the flyback tranformer in the TV, which had a propensity to resonate at the TV's horizontal scanning frequency (somewhere in the ballpark of 15.7 kHz, the exact frequency depending on whether your TV was NTSC or PAL).

I had a "I haven't heard that in ages" moment over the summer; was in some shop in the UK that had a CRT showing their CCTV cameras and could hear the thing well before I could see it. Apparently my high-end hearing's still decent.

CRTs are almost gone; they’re still highly sought after in the smashbros community. :-) IIRC trinitrons are the most highly desired.

Due to the shortage, a "crt vault" was created. [0]

I remember visiting multiple thrift stores ~2 years ago to collect them. The most I had was 6 I think, but I ended up giving them to other players. Here's an example of what they look like at tournaments [1]

[0]: https://old.reddit.com/r/smashbros/comments/3dzqd9/to_those_...

[1]: https://www.youtube.com/watch?v=j_WBBeXzUcQ

The other day my dad, who turned 60 last year, swore he couldn't hear a cicada that was right outside the open window. It bugged him so much he made me go outside with him and point out the cicada. I told him about the mosquito tone, which is obviously much higher, and how mostly only younger people are meant to be able to hear it and played it for him off Wikipedia. He could hear it fine and so could I (30 this year). To hell with the mosquito tone as an anti-loitering device, it's horrible.

Like those high-pitched 'mosquito'-devices installed in places where young people tend to hang out; most adults over 25 can't hear them at all. There is a school here with an apparently inviting set of steps under an awning that activates this device outside of school hours. Passing that building is really annoying.

I'm 39.

Oh God, I saw one of those in Japan outside a store at night, we came near it and I went "what the hell is that noise?", but none of my friends could hear anything. Turned out to be the mosquito thing, which was quite effective in getting me away from that shop.

I was 35 at the time and my friends were 30ish, I guess it varies by person.

It's the babies brought into the shops by their oblivious parents that I feel sorry for. Mosquito devices ought to be illegal, it's noise pollution.

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