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Comment by smlacy | Hacker News Reader

We had one of these as well -- a fairly standard routine of TV after dinner before going to bed quickly taught the dog that the ultrasonic sound made by the "Off" command to the TV meant "everybody go upstairs and go to bed".

You could actually just press that "off" button at any time, and the dog would look around and do that funny "Dog shrug" thing they do, and go upstairs and lie down, even if it was the middle of the day. We had, essentially, a remote controlled dog.

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My dog was similar, but the sound he triggered on was the CRT turning off. You could sit perfectly still and press the off button the remote (so as not to give any body language signs) and he'd wake up, and wander off to the bedroom for the night.

Oh man... I had totally forgotten that sound until you mentioned it.

When I was young and my hearing was better, I think I had a slightly-better-than-normal upper end to my hearing. Often, I would hear CRTs whining that no one else did.

I vividly remember when I realized it. One day in class we were watching a tape and the TV was whining the entire time. After the tape was over, the teacher started talking about what we'd seen, but didn't turn the TV off. I asked him to, because the sound was so annoying. A bunch of kids started saying they didn't hear anything, which made me think I was crazy until one other kid stuck up for me and said she heard it too.

Same here! I remember waiting for a lift where my friends mother worked, a car rental place. I told her I could hear a TV on somewhere, and she insisted there was no TV nearby. I persisted, it was driving me nuts. Finally, she remembered the cupboard above our heads had a TV in it. She opened the cupboard, and low and behold, it was on, on mute. I felt like I belonged in the X-Men.

Lo and behold, oops

Downvoted for correcting my own mistake??

I can also hear a CRT on anywhere in a house/office. One of the best things about the transition to flat screens is that the annoying high-pitched whine that accompanied CRTs has gone away. Now I only hear mode scanning/input skipping flat screens. At the same time, i do feel like I've lost a bit of a super power.

You're hearing the flyback transformer vibrate. I could hear CRT TVs like that, but I haven't been around one in years.

In television sets, this high frequency is about 15 kilohertz (15.625 kHz for PAL, 15.734 kHz for NTSC), and vibrations from the transformer core caused by magnetostriction can often be heard as a high-pitched whine. [0]

[0] https://en.wikipedia.org/wiki/Flyback_transformer

this noise is commonly referred to as coil whine and is made by any high voltage electrical component. The sound comes from the electron gun which has very high voltage passing through it. If you cant hear it you have hearing damage because most crts make the noise just on the edge of human hearing https://en.wikipedia.org/wiki/Electromagnetically_excited_ac...

I could hear that too! Actually nowadays I hear it all the time because I have a tinnitus that is pretty close to that frequency. :-/

Me too! I remember being able to predict that we were going to watch a movie in class because I could hear the CRT whine from the hallways before I even walked into the room.

Haha "remote controlled dog" was funny. You've recreated Pavlov's experiment albeit updated it for our tech century :D

Fantastic story, thanks!! ;-)

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