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When I was a child I could always hear a high pitched whine from nearby CRTs that adults couldn't. I'd always assumed that to be a mechanical effect due to the

When I was a child I could always hear a high pitched whine from nearby CRTs that adults couldn't. I'd always assumed that to be a mechanical effect due to the varying magnetic fields, but perhaps this was the mechanism?

orls 3y ago
That sounds more like coil whine, which is “normal” sound (i.e. moving air) from components vibrating rapidly. That’s not what this paper covers (= more like people’s brains “imagining” sound due to RF triggers) The reason you remember adults not hearing it is because there is a well-documented loss of high-frequency hearing as people age. (Which has even been “weaponised” before; there were stories some years ago about stores blasting high-frequency noise outside to deter loitering teenagers without affecting desirable adult shoppers)
- alex3305 3y ago
  > Which has even been “weaponised” before; there were stories some years ago about stores blasting high-frequency noise outside to deter loitering teenagers without affecting desirable adult shopper Yeah, they should only work for teenagers. Except for when you are visually impaired like me. I'm almost 35 now and still hear those high frequency noise. It is extremely annoying and even borderline painful. Last year I even got the cops involved when a parked car in front of my apartment constantly emitted a high frequency noise for deterring stone marten and I didn't know who the car belonged to. It was a pretty funny interaction in the end because none of the parties involved (except for me) could even hear the noise. But the car owner admitted they had such a device installed. Resulting in them just moving their car.
- NoMoreNicksLeft 3y ago
  I've heard these sounds all my life, as recently as a few years ago. I'll be 50 next year.
  - JohnFen 3y ago
    The ability to perceive high frequency sounds decreases statistically with age -- but that certainly doesn't mean that all people lose the ability to hear them when they're older (and it also doesn't mean that all people can hear them when they're younger). It's a distribution. Probably a normal distribution, but I don't know that for certain.
0xEF 3y ago
Having repaired a few CRTs, this whine typically only happens on aged parts. My son can hear it, but I cannot. From what I understand, as the coils move from vibration over time, this whine gets worse, calling for realignment. The odd thing is I don't remember hearing it much as a kid in the 90's, which is why I associate it with the age/condition of the equipment. These days, every CRT I bring home is the bane of my son's existence if he is in the shop with me, but I can't hear a thing (due to the age of my equipment)
- NikkiA 3y ago
  I definitely heard it in the 90s, in 1990/1991 my university had a lab full of televideo 910 and 905 terminals that were maybe 5 years old, suffering from massive burn-in and a lot of them whined really bad, giving me a headache if I had to use them (the 905s seemed to be worst at this). My first job also involved a dec vt240 with the same features - really badly burnt-in display and horrific coil whine that made me go home with a migraine at least twice that I remember.
dghughes 3y ago
It can be a bad flyback transformer some leads loosen and you get a whine. Power is 60Hz in US and Canada but the whine is much higher than 60Hz. Even a properly working CRT TV had the very high pitch whine. Any kid from the 80s or I guess 90s and back knows of the CRT whine. I recall it so high it's almost like it's in your head as imaginary or you could "taste" it in your 1970s/80s mercury amalgam fillings (maybe that was just me). You lose that ability of your hearing pretty early in life or early teens (loud music damage?) but it couldn't be more than 20KHz the highest pitch of sounds that humans can hear.
actionfromafar 3y ago
It’s the line rate, 15kHz or so. A CRT paints line by line, not only frame by frame.
gpvos 3y ago
That's normal. CRTs emit a faint sound at just under 16kHz, which is in hearing range for most children but not most adults as the upper end of this range naturally decreases with age. The article is about radio frequency electromagnetic waves, at much higher frequencies.
Daub 3y ago
I don't belive I could ever hear CRTs, but I belive I had a similar experience. I once saw a meteor in the night sky of France and also heard the sound it made. I was assured by my father, who knows of such things, that the meteor was way too far away and in too rareified an atmosphere for me to have genuinely heard it's sound. However, I later learned that meteors can emit low and high frequency electro magnetic radiation. Perhaps this was what I heard.
- alasarmas 3y ago
  The sound you heard was most likely caused by the meteor: https://skyandtelescope.org/astronomy-blogs/astronomy-space-david-dickinson/new-take-on-audible-meteor-mystery/ https://skyandtelescope.org/astronomy-blogs/astronomy-space-...
riffic 3y ago
cathode ray tubes make a distinct noise at a high frequency
cameronh90 3y ago
I'm 33 and I can still hear CRTs. It's definitely a sound and not a radio frequency: if you install a spectrogram app on your phone, you can see it at around 16kHz.
brnt 3y ago
It's coil whine. It makes much more sense when you realise that the 16kHz or so frequency is well out of range for anyone over 40. Many things related to noise make sense once you realise all older people are near deaf, compared to the hearing of a 10 year old.

orls 3y ago

That sounds more like coil whine, which is “normal” sound (i.e. moving air) from components vibrating rapidly. That’s not what this paper covers (= more like people’s brains “imagining” sound due to RF triggers) The reason you remember adults not hearing it is because there is a well-documented loss of high-frequency hearing as people age. (Which has even been “weaponised” before; there were stories some years ago about stores blasting high-frequency noise outside to deter loitering teenagers without affecting desirable adult shoppers)

alex3305 3y ago
> Which has even been “weaponised” before; there were stories some years ago about stores blasting high-frequency noise outside to deter loitering teenagers without affecting desirable adult shopper Yeah, they should only work for teenagers. Except for when you are visually impaired like me. I'm almost 35 now and still hear those high frequency noise. It is extremely annoying and even borderline painful. Last year I even got the cops involved when a parked car in front of my apartment constantly emitted a high frequency noise for deterring stone marten and I didn't know who the car belonged to. It was a pretty funny interaction in the end because none of the parties involved (except for me) could even hear the noise. But the car owner admitted they had such a device installed. Resulting in them just moving their car.
NoMoreNicksLeft 3y ago
I've heard these sounds all my life, as recently as a few years ago. I'll be 50 next year.
- JohnFen 3y ago
  The ability to perceive high frequency sounds decreases statistically with age -- but that certainly doesn't mean that all people lose the ability to hear them when they're older (and it also doesn't mean that all people can hear them when they're younger). It's a distribution. Probably a normal distribution, but I don't know that for certain.

0xEF 3y ago

Having repaired a few CRTs, this whine typically only happens on aged parts. My son can hear it, but I cannot. From what I understand, as the coils move from vibration over time, this whine gets worse, calling for realignment. The odd thing is I don't remember hearing it much as a kid in the 90's, which is why I associate it with the age/condition of the equipment. These days, every CRT I bring home is the bane of my son's existence if he is in the shop with me, but I can't hear a thing (due to the age of my equipment)

NikkiA 3y ago
I definitely heard it in the 90s, in 1990/1991 my university had a lab full of televideo 910 and 905 terminals that were maybe 5 years old, suffering from massive burn-in and a lot of them whined really bad, giving me a headache if I had to use them (the 905s seemed to be worst at this). My first job also involved a dec vt240 with the same features - really badly burnt-in display and horrific coil whine that made me go home with a migraine at least twice that I remember.

dghughes 3y ago

It can be a bad flyback transformer some leads loosen and you get a whine. Power is 60Hz in US and Canada but the whine is much higher than 60Hz. Even a properly working CRT TV had the very high pitch whine. Any kid from the 80s or I guess 90s and back knows of the CRT whine. I recall it so high it's almost like it's in your head as imaginary or you could "taste" it in your 1970s/80s mercury amalgam fillings (maybe that was just me). You lose that ability of your hearing pretty early in life or early teens (loud music damage?) but it couldn't be more than 20KHz the highest pitch of sounds that humans can hear.

actionfromafar 3y ago

It’s the line rate, 15kHz or so. A CRT paints line by line, not only frame by frame.

gpvos 3y ago

That's normal. CRTs emit a faint sound at just under 16kHz, which is in hearing range for most children but not most adults as the upper end of this range naturally decreases with age. The article is about radio frequency electromagnetic waves, at much higher frequencies.

Daub 3y ago

I don't belive I could ever hear CRTs, but I belive I had a similar experience. I once saw a meteor in the night sky of France and also heard the sound it made. I was assured by my father, who knows of such things, that the meteor was way too far away and in too rareified an atmosphere for me to have genuinely heard it's sound. However, I later learned that meteors can emit low and high frequency electro magnetic radiation. Perhaps this was what I heard.

alasarmas 3y ago
The sound you heard was most likely caused by the meteor: https://skyandtelescope.org/astronomy-blogs/astronomy-space-david-dickinson/new-take-on-audible-meteor-mystery/ https://skyandtelescope.org/astronomy-blogs/astronomy-space-...

riffic 3y ago

cathode ray tubes make a distinct noise at a high frequency

cameronh90 3y ago

I'm 33 and I can still hear CRTs. It's definitely a sound and not a radio frequency: if you install a spectrogram app on your phone, you can see it at around 16kHz.

brnt 3y ago

It's coil whine. It makes much more sense when you realise that the 16kHz or so frequency is well out of range for anyone over 40. Many things related to noise make sense once you realise all older people are near deaf, compared to the hearing of a 10 year old.