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Comment by skmurphy | Hacker News Reader

Very interesting. I can remember being able to hear a high pitched tone when I was 4-6 shopping with my mother in department stores that seemed to get louder when we approached flush mounted speakers in the ceiling. This article measures the frequencies and explains it's a normally operating feature of the systems.

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Going into Sears used to drive me nuts. My parents finally accepted that I was actually hearing something that they couldn’t, but it took a while.

I don’t know if it was the loss prevention system that was doing it, or what. All I could do was localize it down to being anywhere remotely close to the entrances. And the closer you got, the louder it got.

These days, my tinnitus is constantly ringing at about that same frequency. So, I would probably never be able to hear it again.

Could have been the pulse frequency of old magnetostriction loss prevention rfid tags.

The tone is not meant to be audio, but might be inadvertently emitted by the electronics.

I wear hearing aids and could always hear them as I passed near them. Obviously not the same as real sound as it was just interfering or something.

Exactly this. When I was 17 I worked at a JC Penny store as a stock boy. Every time I approached certain entrances (like the main one that opened into the shopping mall) and other areas of the store my ears were assaulted with a high pitch squeal. Never figured out what it was, nobody else seemed to hear it. I've always had tinnitus, and the frequency always seemed to be the same. In fact, I'm listening to it now.

What year was this? I never encountered such a noise in my stock boy days, but I bet they were a lot earlier than yours (early to mid 1970s).

Have seen a few stores and public places installing speakers pushing out a high pitch tone to irritate youth so they won't hang out where they aren't wanted. Was it some trial run on this tech maybe? :-)

It's designed to be just outside of hearing for adults so only kids and youth can hear it. Did a simple test with our daughter and she can hear quite a bit higher frequencies than we can so apparently it's a thing. Except I can hear higher frequencies than my wife so not very useful I guess.

I wonder how much of this sound pollution disproportionately affects autistic people. We need to make our soundscapes accessible.

Now if the same could be done for bad LED lighting. I hate being somewhere where the whole room is strobing at 100 hz.

Yeup. Interesting how the older LED bulbs are particularly bad for this (and in the UK, at 50Hz). More modern high quality ones seem significantly better.

GP's comment said 100Hz because that's what you get from full-wave rectification of 50Hz mains, so they were talking about that. It'd be 120Hz in countries that use 60Hz mains (e.g. in North America).

Or the idea that the humans are just blissfully unaware while their 'hyper' cat/dog is stuck inside a home with some device screaming 24/7, LED lights flashing, etc.

That’s … a horrible thought.

How does one get a 19khz microphone to check I guess?

My phone shows plausible-looking data up until 24 kHz. I don't have a test device to see if it finds the tone, though

Edit: https://play.google.com/store/apps/details?id=org.intoorbit.... this is the app I use most. Phyphox (https://f-droid.org/en/packages/de.rwth_aachen.phyphox/) seems to only go until 6 kHz but has a lot of other tools. For those wanting to avoid GPlay, this F-Droid app seems to go slightly above 20 kHz but I don't like the interface as much as spectroid: https://f-droid.org/en/packages/org.woheller69.audio_analyze...

My ex got a device to discourage ants. Then forgot where she placed them. Then found out that it was in my daughter's hearing range.

Finding the last one was a nightmare.

Here is the device.

https://www.amazon.com/Ultrasonic-Repeller-Electronic-Repell...

It was

Did it work in its stated goal?

Yes.

I think the dogs can hear our induction stove with ultrasonic whine, but somehow my cat will sleep blissfully in a room with a VGA CRT whining from 30-80 kHz (perhaps quieter than the stove), and used to sit in front of a CRT TV whining at 15.7 kHz so loudly I couldn't stand it without headphones.

When I was a kid I noticed that the adults in my life couldn't hear that CRT sound. My son bought a CRT TV with a built in VCR to use with a Nintendo 64 to get out the last frame of latency. I noticed the other day that I can still hear that sound, but I've always had sensitive hearing and I've always kept amplified sound at a low level and worn ear protection while using machinery, going to motorsports events, etc.

(In the past I have volunteered as a sound man for live music events but I have never been at a venue which I thought wasn't too loud in terms of absolute sound pressure or in terms of there being audible distortion in the amplifiers & speakers, so I haven't made a habit of it. My son won tickets to a 38 Special + Foghat show that we went to last week, I didn't mind the loudness much but it was clear to me they were pushing the sound system just a little too hard.)

I remember in school, we'd often hear the TV whine and know we were watching a tape in class that day without needing to look up at the TV (mounted high in the corner by the ceiling.) The teachers used to wonder how we knew and didn't believe us when we said we could hear powered on TVs.

In these cases, I sometimes wonder if it's my own ears that have distortion at high volume. Would need to try with/without earplugs to verify.

To this day, not one person in the spec reviews in whatever overseas OEM electronics or those split AC units (which are fantastic in one regard) reflects on persistent light in a room where people are sleeping? The worst is encountering AC units when arriving at a hotel that do not have a "display" button to turn off the 20C display in white LED. Are the actual people that make these and make those decisions just tougher or they're just ignorant?

Black sharpie and electrical tape. Never travel without them.

Lately we had both our tenants in our other house (on the same lot) leave, my wife trapped two stray cats inside the house, one escaped, and we are trying to tame the one who stayed.

I moved the TV, XBOX, a $50 PC and almost all of my optical discs (but no books) over there because (1) I won't be so mad if a copy of Disney's Frozen gets pissed on (he's a tom), and (2) if it does the disc will be undamaged and at worst I can discard the package.

That room gets really dark and it doesn't have a switch controlling an overhead light so turning off a floor lamp and then sneaking out the door without creating an opening for the cat to escape (though he's much more inclined to hide than run) leaves me quite happy for the little LEDs and stuff that create just enough light to get from the couch to the door.

I'm not sure I ever managed to hear a 19kHz tone, but I'd say it might have been possible (or the tone was a lower frequency one).

But yes the old CRT whine I could definitely hear

I was young. My mother could not hear it and thought I was just being annoying. This is several decades ago, now I can barely hear my turn signal blinker and am preparing to emulate my father's practice of driving a few miles with his blinker on after signalling a lane change.

One thing that can help is pressing the turn signal lever with less force than is needed to latch it. This should cause the indicator to flash three times and then stop. It’s an operating mode I wasn’t aware of for decades.

Not all cars do this, german car feature? (only VW's I've driven from 2000's onward seemed to have)

My Kia has it as well.

Mazda too

In those cases, you just hold the signal to the point of switch activation, then let go when done.

I've had this feature in Chrysler, Ford, Honda, and Hyundai cars ranging in year from 1995 to 2021.

I think "comfort turn signal" is a feature all newer (2000+) cars should have. I haven't found one from that age that didn't have this feature.

2002 Mazda Miata and 2002 Toyota Camry XLE don't have this. I couldn't find anything about it being a regulation, seems to have become common toward end of that decade though.

Works on my 2009 Honda and 2017 Chrysler.

My 2012 Vauxhall Astra does this.

It's been too long since I posted to edit this, so I'll reply to my own comment: something else my car does that isn't at all unique and some people might be delighted to learn (if theirs supports it too), is that if you hold down the unlock button on the keyfob (rather than press it), it lowers all of the electric windows, and if you hold down the lock button, it raises them. Useful if you left one of your windows open and it starts raining; you don't need to go to the car to shut the windows.

Another German car feature. There's some regulation in the US that requires them to be coded not to go back up (but you can change the coding with a cable). Family has an X5 that will go down as you describe but not up for those reasons.

Long ago I made a conscious effort to turn off my blinker when I’m halfway into the next lane and now turn signals are like entirely subconscious for me.

I've been trying to break that particular habit, on the grounds that most of the purpose behind a turn signal is to indicate entry into a new lane rather than departure from the old one. Not sure what the law says about that, though.

Both equally important.

If the signal is used sufficiently in advance (aka "indicating" your lane departure),

and you're not cutting things so close you need a blinker to fend off cars behind,

then there should be no problem turning it off once half of your vehicle is in the lane.

I'm 30 with mild tinnitus and listen to music too loud but I can still hear CRT whine too, go figure.

Wait, people regularly just don’t hear it?

You'll usually stop hearing the CRT whine in your 20s, 30s if you're lucky. It's at nearly 16KHz and the highest frequency you can hear always drops as you age.

Of course, these days people also regularly don't hear it since CRTs are nearly all gone.

37 here. Definitely still hear if the CRT is on. I have a few 8bits.

Even back in my youth and early adulthood, there was a wide variation on how loud CRTs were between models and individual units. There were some that were close to silent for me, while others were very noticeable.

Most of us don't.

The signal is at a frequency of one cycle per line-second, but there's an idle period while the beam goes back up to the top where it still cycles so the actual frequency will be a bit higher than a simple lines/frame * frames/sec calculation would indicate. Even for broadcast TV that was beyond what a lot of adults can hear (but a lot of kids can, as plenty of posters in this thread have said.) I want to say 15.7khz but I certainly won't swear to that. As your resolution goes up the frequency will go up so some people would be able to hear what resolution a monitor is set to.

Yeah, that one's a bit lower. 15.625kHz or 15.75kHz depending on your region.

I've been tested to 22+kHz, autistic, and older. It was the worst era.

Some of the awful roars of noise I've heard while older people called me a weirdo. CRTs, early checkout scanners, some audio systems.

And back when "as seen on TV" electronic dog whistle trainers were all the rage? Torture.

A few years ago I went to the beach. The place I was staying at had a CRT television. I tried to use it once. I have no idea if something was wrong with it, but it was loud enough to cause pain. Once I turned it off, everything was quiet again and the pain was gone.

I had something similar, when i was young and walking the dog in the evening, i could here a high pitch tone if they had the tv on when i walked by houses.

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