Frequency sounds from TVs

[Jo - the girl]

Do TVs emit some sort of high frequency sound when they're turned on?

Ever since my parents got digital cable, my dad has a bad habit of
turning the cable box off but forgetting to turn the TV off. He can't
tell the TV is still on because with the cable off, the TV screen is
black and there's no audio coming from the speakers.

But I can always tell when the TV's on because I can hear some sort of
sound coming from it. My parents say they don't hear any sound coming
from it and think I must have Superman's ears.

I have no idea how to describe the sound. My guess is that it's
emitting a high frequency noise that my parents just can't hear. I
suppose it's similar to the sound a fluorescent light makes.

Any ideas what the sound is and why my parents can't hear it?


I once heard that there's a cellphone or ringtone that only people
under 30 can hear. It has something to do with the frequency. I don't
know if that's true but maybe that's why my parents can't hear the
sound the TV makes.

 

[William Sommerwerck]

Do TVs emit some sort of high frequency sound when they're turned on?

Sure do. You're hearing vibrations from the horizontal output transformer.
The frequency is 15734.25 Hz.

Women tend to have better HF hearing than men, and everyone's HF hearing
gets worse as they get older. I used to be able to hear to 20kHz or so, but
can now only hear to around 14kHz.

 

[AJ]

The newer teles, including the Flat Panel Plasma and LCD sets may resonate
noises. The power suppliy circuits in these sets run at moderately high
frequencies and do resonate noise.

 

[clifto]

Sure do. You're hearing vibrations from the horizontal output transformer.
The frequency is 15734.25 Hz.

15734.26, but who's counting?

Women tend to have better HF hearing than men, and everyone's HF hearing
gets worse as they get older. I used to be able to hear to 20kHz or so, but
can now only hear to around 14kHz.

I can still hear the horizontal sweep from most CRT sets, but it's not as
prominent as it used to be.

I used to have fun with that. Often with older sets when I'd disconnect my
cheater and put the back on the set, the short disconnect would cause the
horizontal sweep to go out of lock. Whenever the customer would notice and
mention it, I'd just reach for the hold control and put it back in lock,
and say, "Better?" It usually amazed them that I could do that without
seeing the screen, but the sound was so ubiquitous it was hard not to know
when it was off frequency.

 

[Matt J. McCullar]

You're hearing the "ringing" caused by the horizontal deflection of the
electron beam drawing the picture on the screen. As others have said, it's
over 15 kHz, the upper range of human hearing. I can hear it, too; some
folks can walk into a room and just tell when there's a TV set on even with
the audio turned off. Once I walked into a jewelry store and stopped dead
in my tracks because it felt like an ice pick was being pushed into my ear;
the store was using an ultrasonic cleaner for their jewelry and a sales
clerk said that some people do hear that.

Children in particular are quite good at hearing this. Some people have
hyper-sensitive hearing and can hear the deflection of CRT-based VGA
monitors, which is over 31 kHz (normal human hearing range peaks at about 20
kHz). I can't hear that but I have a couple of friends who claim they can.
(One of these is a woman who is totally deaf in one ear.)

 

[jakdedert]

Sure do. You're hearing vibrations from the horizontal output transformer.
The frequency is 15734.25 Hz.

Women tend to have better HF hearing than men, and everyone's HF hearing
gets worse as they get older. I used to be able to hear to 20kHz or so, but
can now only hear to around 14kHz.

15 or so years ago, some manufacturers quit putting power indicators on
TV sets. For the life of me, I don't know why. It sometimes leads me
to turn the set on and off--then on again--because I saw no indication
that the switch press had any effect before the crt ramped up.

I wonder how much was saved in omitting one led...and how much extra
wear and tear on the set was caused by multiple power cycles on each use.

jak

 

[Jamie]

15 or so years ago, some manufacturers quit putting power indicators on
TV sets. For the life of me, I don't know why. It sometimes leads me
to turn the set on and off--then on again--because I saw no indication
that the switch press had any effect before the crt ramped up.

I wonder how much was saved in omitting one led...and how much extra
wear and tear on the set was caused by multiple power cycles on each use.

jak

That's called market research!
Save using less and cheaper parts. Make it less friendly there by
causing users like you for example to shorten the life expectancy of
the mechanical parts and inrush current effects placing strain on the
border line components in place.
You may think that is strange thinking how ever, the off shore
engineers actually get paid for thinking up these tactics in hopes of
you coming back and buy a complete new unit.


--
"I'd rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:

SOME PEOPLE ARE LIKE SLINKIES. NOT REALLY GOOD FOR ANYTHING BUT
THEY BRING A SMILE TO YOUR FACE WHEN PUSHED DOWN THE STAIRS.
http://webpages.charter.net/jamie_5"

 

[jakdedert]

That's called market research!
Save using less and cheaper parts. Make it less friendly there by
causing users like you for example to shorten the life expectancy of
the mechanical parts and inrush current effects placing strain on the
border line components in place.
You may think that is strange thinking how ever, the off shore
engineers actually get paid for thinking up these tactics in hopes of
you coming back and buy a complete new unit.

I imagine the cost saving came first, and the other effects were simply
'ancillary benefits'.<g>

I know that one particular monitor I have, got abused this way because
the cheap panel switch became intermittent. Without the remote in hand,
one could simply not tell whether a switch press actually initiated a
power cycle...unless of course, you pressed the switch, waited (at least
ten seconds) for the crt to warm up, and if not, pressed again. Since I
was using it just for a monitor (no audio connected) this happened
fairly regularly.

FWIW, I 'used' to be able to hear the horizontal frequency when I got a
round a noisy set. These days, I hear it all the time...whether I'm
around one or not (tinnitus).

jak

 

[msg]

Without the remote in hand,
one could simply not tell whether a switch press actually initiated a
power cycle...unless of course, you pressed the switch, waited (at least
ten seconds) for the crt to warm up, and if not, pressed again. Since I
was using it just for a monitor (no audio connected) this happened
fairly regularly.

The 24" Hitachi TV/Monitor I used for fifteen years was similar except that
you could hear the distinctive 'chunk' of the power relay when cycling it
but that didn't convey any on/off state information; fortunately the
horiz. drive components emitted sufficiently powerful audio that in a quiet
room I could tell when it was on.

Regards,

Michael

 

[Warren Weber]

I imagine the cost saving came first, and the other effects were simply
'ancillary benefits'.<g>

I know that one particular monitor I have, got abused this way because the
cheap panel switch became intermittent. Without the remote in hand, one
could simply not tell whether a switch press actually initiated a power
cycle...unless of course, you pressed the switch, waited (at least ten
seconds) for the crt to warm up, and if not, pressed again. Since I was
using it just for a monitor (no audio connected) this happened fairly
regularly.

FWIW, I 'used' to be able to hear the horizontal frequency when I got a
round a noisy set. These days, I hear it all the time...whether I'm
around one or not (tinnitus).

jak

Yep, jak... The crickits I hear often. Even in the winter. Very annoying.
Hearing down to about 3000 Hertz now. W W

 

[[email protected]]

Do TVs emit some sort of high frequency sound when they're turned on?

Ever since my parents got digital cable, my dad has a bad habit of
turning the cable box off but forgetting to turn the TV off. He can't
tell the TV is still on because with the cable off, the TV screen is
black and there's no audio coming from the speakers.

But I can always tell when the TV's on because I can hear some sort of
sound coming from it. My parents say they don't hear any sound coming
from it and think I must have Superman's ears.

I have no idea how to describe the sound. My guess is that it's
emitting a high frequency noise that my parents just can't hear. I
suppose it's similar to the sound a fluorescent light makes.

Any ideas what the sound is and why my parents can't hear it?


I once heard that there's a cellphone or ringtone that only people
under 30 can hear. It has something to do with the frequency. I don't
know if that's true but maybe that's why my parents can't hear the
sound the TV makes.

Standard definition CRT TVs make the pitch others have stated at
15.734 KHz. I used to be able to hear it up until my late 30's - and I
work in commercial TV.

The irony is that by the time you get old enough to _not _ hear it
because of your age, none will exist any more so you'll never know
when you lost the high end.

Men tend to lose high frequency hearing more than women but I don't
know if it's a sex issue or that guys used to work in louder
environments. Loud noise makes the loss worse.

GG

 

[James Sweet]

Sure do. You're hearing vibrations from the horizontal output transformer.
The frequency is 15734.25 Hz.

Women tend to have better HF hearing than men, and everyone's HF hearing
gets worse as they get older. I used to be able to hear to 20kHz or so,
but
can now only hear to around 14kHz.

The deflection yoke and inductors in the horizontal circuit are also common
sources of this noise.

I almost look forward to when I'm old enough to not hear it anymore, I can
walk into a room and instantly tell that a CRT has been left on, not as loud
to me as it used to be though, 10 years ago it was awful.

 

[James Sweet]

That's called market research!
Save using less and cheaper parts. Make it less friendly there by
causing users like you for example to shorten the life expectancy of
the mechanical parts and inrush current effects placing strain on the
border line components in place.
You may think that is strange thinking how ever, the off shore
engineers actually get paid for thinking up these tactics in hopes of
you coming back and buy a complete new unit.

I've been through a few hardware design cycles, it's all about cost, every
fraction of a cent counts with mass produced products. They may not care if
it reduces lifespan so long as it lasts "long enough", but I've never
encountered an engineer who specifically calculated a way to make something
fail sooner.

I push the button once and then wait long enough for the CRT to warm up,
very rarely does the first press not respond.

 

[jakdedert]

Warren Weber wrote:

Yep, jak... The crickits I hear often. Even in the winter. Very annoying.
Hearing down to about 3000 Hertz now. W W

I vaguely remember 'hearing' total silence.

I've had this problem since I was a kid. It puzzled me up into my late
teens when I recognized it for what it was...spurred by odd results on
the hearing test at my draft physical. Reconstructive recollection
traced it back to an incident around 10 yo, firing a cheap revolver
without hearing protection. (Did anybody use hearing protection back in
the 60's?)

Being a 'threshold' issue, it didn't prevent me from a degree of success
as a sound engineer, but has become more annoying as I age. Some times
it's louder than others....

jak

 

[jakdedert]

I've been through a few hardware design cycles, it's all about cost, every
fraction of a cent counts with mass produced products. They may not care if
it reduces lifespan so long as it lasts "long enough", but I've never
encountered an engineer who specifically calculated a way to make something
fail sooner.

I push the button once and then wait long enough for the CRT to warm up,
very rarely does the first press not respond.

Me too, for the most part, except when I was in a hurry...passing the
set on the way to the couch after a long day. I got rid of one years
ago, but I wonder if it would have lasted longer except for this issue.
It's one of the criteria (now) by which I select monitors; but I've
got another one in the family room, and I'm not the one who usually uses
it. I've seen the kids press the button a couple of times, thinking it
didn't turn on....

jak

 

[clifto]

FWIW, I 'used' to be able to hear the horizontal frequency when I got a
round a noisy set. These days, I hear it all the time...whether I'm
around one or not (tinnitus).

I've had tinnitus tones as long as I can remember. The horizontal sweep
frequency isn't one of my built-in tones, though.

 

[clifto]

Warren Weber wrote:

I vaguely remember 'hearing' total silence.

Not me. I remember at age 5, I was in the yard with my mom, and she shushed
me and whispered, "do you hear how quiet it is?" I was too young to think
about contradicting her, but I wondered why the hell she thought there was
anything quiet about all the tones I heard. It was just another noisy day
as far as my ears are concerned.

Since that's as far back as I remember regarding hearing, I kinda doubt
that it was ever different. It did get considerably louder all of a sudden
about five or six years ago, though.

 

[jakdedert]

Not me. I remember at age 5, I was in the yard with my mom, and she shushed
me and whispered, "do you hear how quiet it is?" I was too young to think
about contradicting her, but I wondered why the hell she thought there was
anything quiet about all the tones I heard. It was just another noisy day
as far as my ears are concerned.

Since that's as far back as I remember regarding hearing, I kinda doubt
that it was ever different. It did get considerably louder all of a sudden
about five or six years ago, though.

The 'takeaway' image in my brain is of being in a shallow cave...about
eight years old, I guess, listening to the 'deafening' sound of the
silence. That was probably a couple of years before.... It's not been
completely quiet since then, although, like you, I remember lying awake
at night wondering why there were insect sounds in the middle of winter....

jak

 

[Morse]

Standard definition CRT TVs make the pitch others have stated at
15.734 KHz.

It depends what that 'standard' is! Most of the world do not use NTSC 60.

Morse

 

[[email protected]]

It depends what that 'standard' is! Most of the world do not use NTSC 60.

Morse

OK, 625/50 PAL runs 15.625KHz so it still applies.

from Wikipedia:

"The 4.43361875 MHz frequency of the colour carrier is a result of
283.75 colour clock cycles per line plus a 25 Hz offset to avoid
interferences. Since the line frequency is 15625 Hz, the colour
carrier frequency calculates as follows: 4.43361875 MHz = 283.75 *
15625 Hz + 25 Hz."

GG