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Why Does a Screen Re-Draw Make Noises?

Cliff posted more than 11 years ago | from the weird-software/hardware-tricks dept.

Hardware 236

grungy asks: "On several computers I have owned, I have noticed an audible noise related to large screen re-draws. A hardware guy once hypothesized that the large memory-move operation was creating electronic 'noise' which was then picked up and audibly amplified by my speaker. I unwired my speaker, removed it from the machine and put it in a different room, and the phenomenon still occurred. At this point I assumed it was something going on/emanating from the monitor itself. Now I have a TiBook laptop with an LCD panel. At quiet moments I can still hear it when I drag windows around. I have tried doing big memcpy's & the like, I don't get the same noise. I've been wondering about this for years. Anybody know what gives?"

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If a tree falls in the woods... (-1, Troll)

Anonymous Coward | more than 11 years ago | (#5393808)

Does it sound like 'FIRST POST' ?

Static electricity? (2, Informative)

EvilMal (562717) | more than 11 years ago | (#5393827)

Is it associated with a large change in brightness? Like in drawing a white box on top of a black area?

It could be static electricity, as it is suddenly going from one number of electrons to a very different number of electrons hitting the screen.

Gee, it's great to have an electrical engineer as a dad...

Re:Static electricity? (1, Insightful)

Anonymous Coward | more than 11 years ago | (#5393864)

that might be true if it were a crt, but it's an lcd. there are no electrons hitting anything, just crystals interacting with light.

Re:Static electricity? (3, Informative)

Goldsmith (561202) | more than 11 years ago | (#5394124)

Not quite true.

Remember that light itself is electromagnetic radiation. The change in screen color (as suggested by one comment) might be enough to make some small amount of noise.

More likely, it's an induced response from the screen material to the changing charges across the screen. An LCD works by putting an electric field across a liquid crystal to allow/block light. As you redraw, those electric fields are changing. Those fields might have a small effect on actual material the LCD is made of. Those materials might have a small sensitivity to electric fields, and there is almost certainly some small charge even from dust on the screen.

So... after all that, it's my guess that the clicking noise (I've heard it too, you're not insane) is portions of the plastic on/in the screen either expanding out or contracting in with the field, essentially "popping" in an out.

Another thing it might be is electrically charged dust (dust does not have to be neutral) moving around on the screen. Try dusting your screen and seeing if that does anything.

Re:Static electricity? (1)

rve (4436) | more than 11 years ago | (#5393892)

I noticed the same years ago, and assumed it was static, just like the noise a TV tube makes when you switch channels. I never heard any noise with an LCD screen, and i think the OP migth be experiencing some psychological rather than real effect. Or has anyone else heard an LCD screen make noises?

Re:Static electricity? (1)

aminorex (141494) | more than 11 years ago | (#5393924)

Yes. I've had laptops that made sounds when
significant screen blits occurred. In particular,
a Dell Inspirion 5000e uxga. That's an ATI Rage-M
video chip. As I recall (my daughter has been
using it lately), I only heard it with XFree86,
not with Win2k, and it sounded like it was composed
of a lot of rapid chirps or clicks (~50 msec),
but had a principal harmonic in the kHz range.

Re:Static electricity? (1)

cymen (8178) | more than 11 years ago | (#5393945)

Same thing but on an XGA Dell Inspiron 4000 with same video chip (ATI Rage-M). I can also hear the same things on heavy memory operations like kernel compiling (of course the hard drive has to be somewhat silent).

Re:Static electricity? (4, Interesting)

Mad Quacker (3327) | more than 11 years ago | (#5393984)

Just to add to that, there are quite a few people that can hear the extremely high-pitched whine of CRT's scanning - we can tell if a TV is on in a room without looking with it on mute. The channel changing sound is much lower pitch so almost anyone can hear that, not to mention the static discharges that can occur. It's no surprise to us that electronics make noise, in fact sometimes it can be downright painful. I used to have this 32" inch TV that would whine to the point of pain until it warmed up 5-10 minutes later. Of course as I cover my ears everybody else doesn't notice a thing. Good ears can be a curse :(

Just wait a while... (1, Insightful)

Anonymous Coward | more than 11 years ago | (#5394403)

...When you're 40, you won't hear it anymore. Young ears hear much higher-pitched noises than old fogie ears.

Re:Static electricity? (2, Interesting)

teamonkey (553487) | more than 11 years ago | (#5394549)

I can hear that too. I can tell if a TV's on nearby - in another room or even downstairs. Always have been able to, although it was much more noticable when I was younger. High frequency devices are less noticable though. What about the details on screen? I find that a white screen makes a higher-pitched noise than a blank one. On another note, my old monitor used to make high-pitched noises every so often which could be solved by giving it a sharp whack.

Re:Static electricity? (1)

TheCrimsonUnbeliever (638597) | more than 11 years ago | (#5395119)

I have the same 'feature' as both parent posters

It has been useful a few times in life - though I have never experienced it till the point of pain

Re:Static electricity? (1)

andfarm (534655) | more than 11 years ago | (#5395930)

Most people without some degree of hearing loss can `hear' CRTs like you describe. It's well within the normal adult human hearing range -- most people just don't listen for it.

Re:Static electricity? (4, Informative)

You're All Wrong (573825) | more than 11 years ago | (#5394245)

LCD actually change physical state, i.e. there is a mechanical change. Enough of those at the same time, and there will be some sound. A little like piezo-electric shriekers, but much smaller, and with much smaller movement, and only a single pulse of movement rather than repeated oscillation.

My Psion 5 used to sing a merry song to me all the time as things changed on screen. Almost everything LCD makes these noises in some quantity. I do have very sensitive ears though, so perhaps not everyone hears them.


Re:Static electricity? (1)

You're All Wrong (573825) | more than 11 years ago | (#5396100)

And before anyone claims that I was hearing the back-light, I wasn't. The backlight is a positive _roar_ compared to the LCDs. On the Psion the backlight could be turned on an off at will, and the redraw sounds were audible when the backlight was off.


Re:Static electricity? (1)

aminorex (141494) | more than 11 years ago | (#5394009)

If it's anything like my laptop experience, it is
most notable when you drag a window with redraw on.
It's quiet, but very clearly perceptible in most
environments (not on a passenger jet in flight,

Re:Static electricity? (2, Funny)

dotgain (630123) | more than 11 years ago | (#5394545)

Hehe, for things that (mainly) don't have speakers monitors sure make some strange noises eh?

I've got ones that fart, crackle and squeal. Everybody! Degauss on 3..2..1..

Re:Static electricity? (1, Interesting)

Anonymous Coward | more than 11 years ago | (#5395463)

i saw this website once where a guy was using his screen refresh rate to generate AM signals and transmit music to a radio nearby.

could it be the hard drive? (1) (562495) | more than 11 years ago | (#5393830)

In my 3D grafix programming life, i never heard these noises :)

Re:could it be the hard drive? (1)

grundy (151557) | more than 11 years ago | (#5395265)

Y'know, that is interesting. On my machine, I can hear an 'ls -l' through the speakers, but it clinks in sync with each line showing up on screen, but doesn't clink with other hard disk accesses (and only in X, not from a text console). But, when I used to have Win95 on that machine years ago, I could hear hard disk access through the head phones, very light. The other part of this is the tower is in a pretty sound tight cabinet, I don't really hear much from it, and it definately comes through the monitor speakers.

Re:could it be the hard drive? (1)

Oculus Habent (562837) | more than 11 years ago | (#5396042)

That's shielding, I think. Only really good speakers are shielded, and all sorts of things come through when you don't have shielded speakers.

Various systems/speakers I've used I have heard hard drive access, monitor changes, even mouse movement. Though, my favorite speaker issue is my current speakers pick up a country station when the volume is all the way down. You can make it out when it's quiet, especially at night.

Electromagnetism (5, Informative)

Mad Quacker (3327) | more than 11 years ago | (#5393831)

Whenever you have a flow of current, you will have a magnetic field generated, and that field reacts with the environment to cause motion. Even though computers are 'digital' doesn't mean that some how they are immune from the all the laws of electromagnetism we use to design analog devices like speakers - it's all the same thing. If nothing else, there is always the earth's magnetosphere to react with like a speaker's coil to it's magnet.

It's the same reason electrical transformers hum, and fluorescent lights buzz.

Re:Electromagnetism (5, Interesting)

Smidge204 (605297) | more than 11 years ago | (#5394865)

I wasn't aware that humans could 'hear' electromagnetic waves. :)

The reason transformers hum is because their cores are vibrating in response to the magnetic fields they're subjected to. Same with flourecent lights (which have transformers in them).

But yeah, just about every AC power appliance gives off a "Hum" of electromagnetic waves, and digital devices, with their constant pulsing, do it as well. And preventing the two from interacting is big business.

Some good examples from personal experience:

Trying to record some audio clips, but when I play them back, half of them have a STRONG buzz in the background. So loud you can barely hear the recording. Turns out my mom turned on her ceramic kiln in the basement (which sucks a lot of juice), creating strong interference. Sure enough, when the kiln turned off, the problem went away.

If I have the volume up, not only can I "hear" the screen redraws, but the mouse move, my keyboard pulse, and my network card go to work. If I have the headphones on and the volume all the way up, I can hear the hard drive working, too. (Interestingly, I'm reminded of this one government "safe room" that was specifically sheilded to stop these pulses, since it would be possible to catch and decode them to figure out what the input devices are doing. eg: passwords and other text)


Re:Electromagnetism (1)

david duncan scott (206421) | more than 11 years ago | (#5395322)

More than one room -- I believe every US embassy has such a room, shielded to the extent that only battery power is used inside. No holes in the Faraday cage once the door is closed.

I have no idea what they do about air. Perhaps a baffled air duct can be used, or maybe they just work quickly. :)

Re:Electromagnetism (1)

cdrudge (68377) | more than 11 years ago | (#5395520)

Or perhaps just a copper wire screen over a regular air duct? A Faraday cage does not have to be solid to be effective.

Re:Electromagnetism (2, Interesting)

david duncan scott (206421) | more than 11 years ago | (#5396163)

Looks like milspec gets tougher than screen, judging by this, [] which describes a honey-comb waveguide approach. (That company also makes welded steel rooms, with no fasteners used in the seams -- just solid steel everywhere.)

Re:Electromagnetism (4, Funny)

Sentry21 (8183) | more than 11 years ago | (#5395068)

It's the same reason electrical transformers hum

Because they don't know the words?


Hrmmm (1, Insightful)

Anonymous Coward | more than 11 years ago | (#5393834)

I hear noises too... but my doctor solved that problem :-)

But seriously, could the monitor cable be near a power cable or speaker cable? I can hear interference whenever the two are nearby.

Can you hear the noise even if speakers are not connected or nearby?

Maybe this page (see the section "noise interference") may help:

Re:Hrmmm (1)

dotgain (630123) | more than 11 years ago | (#5394526)

I know the poster has already said he's disconnected his speakers and the problem still persists, but the cdrom audio -> snd card cable picked up noise from everything in my box, gfx redraws, hdd access of course, you can even hear the tray motor when the cdrom opens.

So I have my CD mixer all the way down for the most of the time I don't use it. Next cdrom must have spdif out.

BTW poster, memcpy()'s won't do it - they only copy within main memory. Graphics operations will cause data to pass from main memory to gfx card. This IMO will be more likely to recreate the problem. Tried a different graphics card?

All the little gates. (2, Funny)

bradipo (94457) | more than 11 years ago | (#5393839)

Maybe it's all the little ``gates'' opening and closing inside the computer as the electrons flow through system. I have created this same noise effect by ping flooding a host in a test lab environment on a 100Mps Full-Duplex switched network---the network card was actually a four port and I may have been pinging all four interfaces from different systems.

Tempest Radiation (3, Funny)

Anonymous Coward | more than 11 years ago | (#5393841)

LCDs do not have the electro-magnetic radiation that can be picked up by passing DOJ vehicles for license validations.

In late 1997, a secret comittee was formed and ushed in a new era of aural-based tempest radiation sensors. They created a bill that stipulated all LCD monitors needed audio broadcasting capabilities for governmental remote viewing. It was rushed through congress during secret underworld briefings and eventually passed at the Grand New World Order Council, codified in January, 1998.

Today these signals are still somewhat perceptible in the lower frequencies, but they emit a wide spectrum for large data broadcasts. Simple listening devices can pick up many user metrics, and are not limited to merely what's displayed on the screen.

I hope this answers your question.

I Hear Dead Screen Redraws (0)

CFusion (302547) | more than 11 years ago | (#5393852)

This is consistent with the sound a monitor will make when tapped by the RIAA or the DEA (looking for bong dealers). You should immediately unplug the monitor, put it in the shower, and let the water run for approximately 15 minutes. Be sure to apply a good screen massage.

Might be related to tinnitus (1)

Chilltowner (647305) | more than 11 years ago | (#5393854)

I'm not saying you're crazy, but tinnitus or a related phenomenon could be part of the reason for the sound you hear. It's surprisingly easy to habituate yourself into hearing buzzing, humming, or other types of noise that can be interpreted that way. There are, of course, other possible reasons for why you hear the sounds (degaussing on a CRT, maybe). And there are certainly other physiological causes for tinnitus, too. But it's not impossible that you're causing yourself to hear sounds when you expect to hear them. There's an interesting article [] on habituation and treatment of tinnitus that might be related. The human brain is truly a marvel.

Just one consideration among others.

Noisesssssssses, yesssssss! (4, Funny)

orthogonal (588627) | more than 11 years ago | (#5393871)

I have noticed an audible noise related to large screen re-draws.

Do the noises sound like sounds?

Do the sounds sound like words?

Are they talking?

Talking to you?

Telling you to do something?

Something like...

Kill! Kill! Kill?

Kill the nassssty hobbitses?

For the precious, preciousssss, preciousssssss


Yessssss. Yesssssss. Kill the hobbitses!

Re:Noisesssssssses, yesssssss! (4, Funny)

Lord Bitman (95493) | more than 11 years ago | (#5393879)

no, it's more like a clicking sound.

Re:Noisesssssssses, yesssssss! (0)

Anonymous Coward | more than 11 years ago | (#5394295)

rofl. well done. i can't stop chuckling.

Re:Noisesssssssses, yesssssss! (0)

Anonymous Coward | more than 11 years ago | (#5394638)

it's the same noise that you get when you do a monitor degauss..?

Re:Noisesssssssses, yesssssss! (2, Funny)

Pogue Mahone (265053) | more than 11 years ago | (#5394384)

Or is it humming?

If it's humming, that's because it doesn't know the words.

Perhaps both? (1)

'The '.$L3mm1ng (584224) | more than 11 years ago | (#5393890)

Perhaps it was the CRT on the first computer you mentioned and the speakers on the second. Since it was a laptop, it probably had speakers.

My current computer makes such noise when using my Plextor burner - unless I switch it off in the mixer.

And my old computer made such noise with almost every operation, disc usage, mouse usage, hard drive and so on. Simply because it had speakers attached to the front of the case (a so-called Multimedia PC). The output of the sound card had to be plugged into the back of the case. I guess it was the radiation inside the case that influenced the signal on the way from the back of the case to the speakers at the front. It was really loud, but I could easily tell when something was wrong with my computer - then the sound changed :)

experiment (2, Insightful)

Lord Bitman (95493) | more than 11 years ago | (#5393906)

have you tried turning /up/ the volume of the speakers?
yes, I know "The speakers unplugged blah blah blah", I'm not saying that it doesnt exist when there are no speakers, but the speakers could indeed pick up the noise.
When I heard this noise, however, I looked up on google, it said to turn your soundcard volume down from 100%, and boom it goes away.
Now let me ask you this: have you unplugged your /internal/ speaker?

I used to get that... (1)

Pathwalker (103) | more than 11 years ago | (#5393942)

I used to have a weird faint sound just on the edge of hearing show up, not when I was moving windows around but when I was sending packets over the network.

Whenever there was a lot of network activity, If everything was quiet, I could hear a faint sound.

I assumed it was just a cap vibrating in my cheap ethernet card, and swapped it out for a better one (when I finally switched away from 10b2).

The sound went away after that.

Re:I used to get that... (1)

WhiteDragon (4556) | more than 11 years ago | (#5395044)

reminds me of an old unix admin who tee'd his syslog to /dev/audio, so he could hear a tick when something happened. Sort of like a Geiger counter, if it starts happening fast, you know something is going on (automated break-in attempt, DOS, slashdotting, etc.)

Noises (0)

Anonymous Coward | more than 11 years ago | (#5393947)

My tibook (800DVI) also makes a very low subtle static-raspy-buzz sound when I drag larger windows around. I think it's coming from the speakers. The noise happens even if sound is muted. I've noticed it for some time.

Re:Noises (1)

Forss (650095) | more than 11 years ago | (#5394764)

My PB 800Mhz makes the noises too, and my friend's PB 1Ghz...Sometimes the sounds are even quite loud - but usually I just hear the "very low subtle static-raspy-buzz sounds" you described.
(Just opened a the Forssfeed [] )

stop eating mushrooms (4, Funny)

Bastian (66383) | more than 11 years ago | (#5393949)

or at least get them from the grocery store instead of collecting them out in the forest.

That should solve the problem quick.

Re:stop eating mushrooms (0)

Anonymous Coward | more than 11 years ago | (#5394063)

But the ones on the lawn taste paisley!

Sounds during display of graphics, events. (1)

RogueScientist (575110) | more than 11 years ago | (#5393972)

many systems use series of coils and other devices to format the voltages and frequencys with in certian ranges. I have noticed that duing some screen redraws I would get audable sounds on a PS-390 Evans & Sutherland graphics display while displaying vector graphics and no weird sounds in text mode. The system used a CRT, and other odd interfaces, but there was no speaker as such, and it would create audable emissions, and they could be viewed on a osciloscope with a microphone attached as input... I would reccomend that you approach this as scientificaly as possible by actually measuring the sounds, recording the sounds nad doing frequency analysis on the sounds. Then you could better asssertain what the problem is. On my current quick silver G4 there was a speaker hiss problem where you could hear audable noises out of the internal speaker during some operations with menus and graphics. The only solution was the attachment of Apple Pro Speakers to the G4 audio out port, though if you hold the speaker up to your ear you can still hear the noises, so it still has some cross over with the sound system.

Possibly the power supply (4, Informative)

toybuilder (161045) | more than 11 years ago | (#5393977)

The hissy-screechy-screech-screech that you're hearing might also be coming from the power supply. To the extent that it would carry into your audio circuit, electrical noise would easily translated to acoustic noise through your speaker/headset.

However, it's also possible that you have a marginal power supply that operates at switching frequencies that approaches human-audible frequencies; or the actual current draw changes from high-speed memory transfers within the graphic sections (board) has a human-audible frequency component to it that actually emanates from (say) the torroids in the supply.

People with very sensitive high-frequency hearing can sometimes tell the brightness of a television screen just by listening...

This could also happen from other activity -- I once had a 386 PC which, when running DOS, would emanate the tell-tale sound when it was waiting for keyboard input. It was kinda neat, actually -- I could go read other things while waiting for a program to finish its calculation -- and I didn't have to keep looking up at the screen...

I have this happen too! (1)

DiSKiLLeR (17651) | more than 11 years ago | (#5393985)

I have this happen too!

I never noticed it on a PC before (mainly because they are so noisy, hdd's spinning, several fans inside spinning, air blowing, etc).

But on my Powerbook G4, i have DEFINITELY noticed this happening.

When its unusually quiet (usually late at night) when not a sound can be heard, and the powerbooks fan and hdd is off, i can very clearly hear this sound when i move windows around!

Its totally bizzare.... and its like a clicking sound that another poster described.

Its an extremely quiet sound, however, and usually you would never hear it unless its unusually quiet and your ears have had time to adjust to the minutest sounds.

If you have a tibook, try it.

I dunno if its possible with a normal PC, though, since they are just so noisy.


Maybe your power supply/main adapter is giving up (1)

snowbird7 (653805) | more than 11 years ago | (#5393994)

This happened to me once. Try to determine if the noise comes from the LCD or from the computer itself. In the latter case, you should probably replace your main adapter as it's likely to give up soon. Normally happens when it's deteriorating or not strong enough in the first place.

I have seen (heard) this before (1)

RGRistroph (86936) | more than 11 years ago | (#5394064)

Most notably on a Sun UltraSparc from which you could hear a hiss coming from the case (not the monitor) when scrolling a large body of text through an xterm. There were no speakers on the machine. I could cat a large file and hear the memory chips hiss. I think it was the memory chips from the location on the front right side of the case.

This was very repeatable, and could be demonstrated to anyone. I've had similar noises from other machines, but the fan usually drowns it out to where most people can't hear it and you aren't sure.

ME 2 (1)

hswerdfe (569925) | more than 11 years ago | (#5394096)

OK I have only noticed this on my latest computer.

its not only on redraw even just moving the mouse somtimes ..
but moving windows makes it louder.
it comes from the speekers and goes away if I turn them off but still its crazy....

p.s. My girlfriends, roomates computer talks all the time, no lie, she has a tv card hooked up to cable and ALL the time you hear a low wisper of the the TV comming through even if arn't watching TV at that time....

its fucked up....

Re:ME 2 (1)

PotPieMan (54815) | more than 11 years ago | (#5394337)

p.s. My girlfriends, roomates computer talks all the time, no lie, she has a tv card hooked up to cable and ALL the time you hear a low wisper of the the TV comming through even if arn't watching TV at that time...

That's not too surprising. She's put a huge RF receiver in her computer case. The shielding on most TV tuners is not all that great, meaning it will interfere with other components.

I got in the habit of muting the line input to stop the hissing.

Re:ME 2 (1)

root 66 (72128) | more than 11 years ago | (#5394340)

Is she buying a lot of well advertised products lately?

Yep, me too. Bad RF shielding. (2, Interesting)

arekusu (159916) | more than 11 years ago | (#5394103)

I've heard this on every computer I've owned, going back 14 years to my Apple IIgs. Any CPU operation (tight loops reading memory especially) could be heard as pitched tones on the audio out, especially noticable when listening with headphones. On the IIgs, I had a stereo "Audio Animator" card and always figured it was crappy RF shielding. You could hear a scale, tones changing as you moused over each item in a menu.

But it happens on my other computers too, to larger or smaller degrees. On my TiBook, it's pretty noticable when the fan/drive are spun down. I program in Cocoa/GL and you can hear the tone change just by creating an NSTimer with different frequencies, and using it to do graphical operations. Most of the time, this results in a low 60Hz "hum."

I think it's due to RF interference between the audio portion of the board and whatever else is nearby. It seems more prevalent on laptops where everything is packed closely together but it's not limited to laptops, or LCDs.

Somebody should write an app that plays one-channel melodies with the RF noise... ;)

Re:Yep, me too. Bad RF shielding. (4, Interesting)

Scorchio (177053) | more than 11 years ago | (#5394512)

Presumably you're refering to this event at the Homebrew Computer Club back in 1975... (snipped from this article [] )

The Altair may have been frustrating, but it drove the nerds to experiment, finding real uses for the useless box, turning it from a curiosity to a computer.

Lee Felsenstein
Steve Dumpier set up an Altair, ehm laboriously keyed a program into it. Somebody knocked a plug out of the wall and he had to do that all over again but nobody knew what this was about. After all, was it just going to sit and flash its lights? No.

Roger Melen
You put a little eh transistor radio next to the Altair and he would by manipulating the length of loops in the sofware - could play tunes.

Lee Felsenstein
The radio began playing 'Fool on the Hill'....Da da da, da da da....and the tinny little tunes that you could tell were coming from the noise that the computer was generated being picked up by the radio. Everybody rose and applauded. I proposed that he receive the stripped Philips Screw Award for finding a use for something previously thought useless. But I think everybody was too busy applauding to even hear me.

Roger Melen
It was a very exciting thing, it was probably the first thing the Altair actually did.

On a related note, my old BBC micro used to pick up interference on it's internal speaker, which could actually be used for some basic debugging. You could tell if it had crashed, or whether it was still running round a particularly heavy maths loop, etc...

CPU (0)

Naikrovek (667) | more than 11 years ago | (#5394111)

When your CPU comes on and off of the HLT (halt) instruction, it creates a tiny electromagnetic field that is perceptible by your sound card.

you don't hear it on file copies because the CPU is steadily on, and not halting.

This is much more perceptible on Linux than on Windows (with the same exact computer) because linux likes the HLT instruction a lot more than windows does.

This is what I think it is, anyway.

Re:CPU (1)

kasperd (592156) | more than 11 years ago | (#5394309)

When your CPU comes on and off of the HLT (halt) instruction, it creates a tiny electromagnetic field that is perceptible by your sound card.

Indeed I have had the very same problem with my computer. For a long time I simply added no-hlt to my kernel command line to remove the noise. To demonstrate that this was really the cause, I wrote a DOS program [] to provoke lots of noise on any computer suffering from this problem. The Turbo Pascal source [] is also available. (Don't try this program under Windows, It will not work).

Having lived with the no-hlt option for a long time, it came to my mind, that always wasting power in the CPU just because I occasionally want to use the soundcard without noise was stupid. Instead I wrote a patch [] that allowed me to switch the HLT instruction on and off as the soundcard driver was loaded and unloaded.

no HLT eh (1)

WhiteDragon (4556) | more than 11 years ago | (#5395196)

:-) yet another reason to be running
or some other [] ways [] to tie up [] your cpu. After all, if you are not using your processor, those cycles are just going to waste.

Electrical noise... (1)

Kevin Burtch (13372) | more than 11 years ago | (#5394113)

I'm not sure exactly what you mean by moving the speaker to a different room... did you reconnect it? (unplugging it is sufficient, moving it is pointless).

I have heard monitors before... old Hitachi made Suns (as used on IPCs and SPARCstation 1s) with bad flybacks (painful if you have a high range of hearing). The tone changed slightly with the brightness of the screen, but was always there.

I am typing this on a computer that makes noise whenever I move the mouse or type, or during screen drawing functions. These sounds are definately coming from the speakers. If this is what you are experiencing, then your friend was exactly right. You will be more likely to hear it with cheaper sound cards/chips... and different video chips. The one I have is a horrible on-board sound-chip as used on a Tyan Thunder 2 (dual P-II board w/on-board sound & SCSI), the OPL3-SAX. It may also be the design of the board rather than the chip. Part of the problem is the video card, I'm using a Banshee in this box. When I toss in a sound card (instead of using the onboard chip), the annoying noise is greatly deminished, but still there (if you listen closely).

Re:Electrical noise... (1)

archiBEN (645920) | more than 11 years ago | (#5394344)

apple have done anything but acknowledge this noise - i started a thread in the apple discussions forum back in august last year: Ta gAVhif.5@.3bb97c21

lots of people were getting this noise, particularly after the upgrade to jaguar (quartz extreme!).

btw - don't think that it is actaully doing any damage as i first thought. living with it is easy - turn the music up!

BOFH: (4, Funny)

Eneff (96967) | more than 11 years ago | (#5394158)

*Turns Calendar Page*

Looks like it's Duplicated backplane dereferencing signal.

You see, the operating system has to keep a buffer of the screen in memory, and similar to dereferencing a pointer, the dereferencing of this backplane, or buffer, temporarily distorts the signal on monitors that haven't been serviced lately.


Luckily, this is something you can quiet fairly easily. Do you have a screwdriver?

This might seem a bit odd but I've heard it. (0)

Anonymous Coward | more than 11 years ago | (#5394167)

No, really, I have. Especially if I set the CD audio volume up.

See I have headphones, if and you use headphones you can really here ANY activity on the bus, and thats not me being insane. Like any time and major "traffic" on the PCI bus takes place and I have the CD audio volume up, I can hear it. I guess the IDE controller doesn't isolate itself from the bus well enough.

I really don't know a lot about the PCI bus, but doesn't it have a high-impedience state (tri-state bus) for any device that is not active (hey just learned that in my digial-logic class)? Maybe it doesn't, I dont know. If it doesn't is that because it would cause a larger current drain due to the high impedicance? Not sure, really exhausted atm so I'm probably not making a lot of sense but oh well sorry.

Anyway, some of my friends thought I was nuts because I would say I could "hear my computer". But I let them try on the headphones and then I did a 'ls -alf' on /usr/lib or loaded up a web page, and they could hear the transfers on the bus. Its not a "normal" sound, more of a really dampened sound of like when computers used audio tapes to store programs and you played the tape in a audio tape player.

Its the voltage down-converter on the backlight (1)

killionk (75557) | more than 11 years ago | (#5394177)

Apple has long acknowledged this issue. It has been in every laptop they have made. The problem is a capacitor in the voltage down-converter.

Previously the down-converter was in the top of the clamshell, but now it has been moved to the bottom case near the motherboard.

You can hear the same hiss/hum from the ballast in a florescent light. Since the backlight on a LCD is really just a thin florescent light.

If the issue is exceptionally bad, and easily reproducible you can send the machine into the depot for repair, worst case scenario you will not have your machine for up to 7 days.

Solution (4, Funny)

D.A. Zollinger (549301) | more than 11 years ago | (#5394222)

You are hearing noises from yout computer?
Ok, this is what you need to do:

Listen to music. LOUD music. For years on end. Eventually, you will get to the point where you will no longer hear the noises coming from your computer. Problem solved!

Ehh? What did you say? Speak up, son!


Anonymous Coward | more than 11 years ago | (#5394240)

It's the bus'es. When large amount of data passes the bus (e.g. the PCI bus), the sound-card might pick up these, since the sound card constantly listens for new sound-input.

Interference? (1)

JM Apocalypse (630055) | more than 11 years ago | (#5394247)

I think I am having a similar problem, but on a different level. My server, which I newly built for $80, has an odd problem with the fan speed. I believe it may be caused by signal interference or something along those lines. Any extra interference will cause the fan speed to move up, for some strange reason. This usually occurs when the computer is doing any processing, like storing a file or dealing webpages. It is really odd, but I only hear it if I am trying to listen for it. So just stop listening and the voices will go away. (That is, unless you have a whole new kind of mental illness, where the voices control you, instead of you just taking suggestions) Something similar may be happening with the monitor, but I am not sure.

If all else fails, check yourself in to the local, conveniently located loony bin. Hey, it worked for me!

easy... (1)

gid13 (620803) | more than 11 years ago | (#5394320)

thanks to microsoft's continuing innovation, the OS can make sounds whenever certain events (like opening windows) happen... all you have to do is turn down the volume ;)

Noise.... (5, Funny)

keoghp (457883) | more than 11 years ago | (#5394345)

They are all wrong...
It's a little guy in the computer with chalk, drawing the pictures on the screen. Sometimes when the screen "freezes" - it's him taking a break.

After a long spell at the coomputer you can usually hear him gasping for breath.

When he has run out of colours and he only has blue left - that when you get the BSOD.

Oh man, me too (2, Interesting)

eamonman (567383) | more than 11 years ago | (#5394381)

Before, with CRTs and cheap LCDs, anytime that I moved a big window (typically bright, say all white), and wiggled it around the desktop, I heard something similar to a, "wheeeee, weeeeee" kind of sound (the 'wheee' matching the window movement). Of course, this was a very very high pitch sound; a quieter and higher pitched version of the whine that TVs and crappy old CRTs make. Now I have a new and really nice LCD... I can't really hear anything, but then again, maybe I'm just getting old.

Isn't it great to know you have good hearing though?

This is a little OT but... back when I was a kid, I think I had even better hearing... I used to stay at my grandparents' house, and I could sense people walking down the hall to my room, no matter how quiet they were. The floor didn't squeak, and my grandmother used to walk around softly. But I could tell when she was coming. Basically, I would hear what seemed to me a lack of noise approaching; there was a lot of ambient noise from the living room (the windows were open which means lots of trees, birds, wind, etc. to hear), so someone walking down the hallway towards my room from the living room seemingly blocked some of the sound. It was very slight, but it was enough so I would usually be looking up at my grandma when she turned the corner to my room. I've had other experiences, like hearing if someone was sticking their hand in front of my face when I was blindfolded (it had to be in a fairly quiet room however).

Sigh, I miss having my good hearing. 25 years and lots of concerts, New years festivals and 4th of Julys will do that. It would be so helpful now to have that hearing, especially when my boss walks to my cubicle ;)

AM Radio waves (1)

mushon (236351) | more than 11 years ago | (#5394400)

Generally computer screens emit AM radio waves whenever they work, it is possible that when you do a large screen re-draw it eminates a specific wave length that affects your speaker...
Personally this has never happened to me but it's possible.

BTW it is possible to capture your screen using an AM reciever, also the reverse is possible as well - you can use your screen to broadcast music (by emulating the music into a screen image that will broadcast the music) I even saw a program that does this for MP3, but I forgot the name...

Re:AM Radio waves (1)

Blob Pet (86206) | more than 11 years ago | (#5395123)

If I adjust my AM radio to a frequency that emits only static, I can put my TI-82 up to it to get sound effects when I play tetris.

I hear the NIC on my laptop buzz... (1)

wimbor (302967) | more than 11 years ago | (#5394482)

On a Sony VAIO FX205K (european Model) you can hear the NIC card buzz (or maybe CPU?) when large quantities of data are copied over the network (e.g. a 200MB file)...

Since the PC has a TFT screen and an external power supply, I doubt that these have anything to do with it...

Re:I hear the NIC on my laptop buzz... (1)

Nize (469460) | more than 11 years ago | (#5394903)

I can confirm this, I have an IBM ThinkPad T22, and when I transfer large files over the NIC, a kind of buzzing sound is emitted from underneath the keyboard. It has nothing to do with the harddrive, as I can reproduce the sound with TTCP.

RF noise and the ZX81 (1)

osd1000 (67634) | more than 11 years ago | (#5394499)

The fact that computers generate RF noise was put to great use by a program for the Sinclair ZX81 (which had no sound hardware). The program caused oscillations which, if you turned the TV's sound up, were audible as tones.

Noise (1)

The3ofme (645795) | more than 11 years ago | (#5394508)

I have a Compaq Evo I use at work. If I am listening to my headphones, the cheap ones or the hundred dollar ones, I get a static noise that changes pitch and cycle rate when I type, move my mouse, click on things, open files... It is really interesting. It is almost like the computer is telling me what it is doing. Of course this becomes irritating after a while, because I have heard enough from it now.

Re:Noise (1)

cybermace5 (446439) | more than 11 years ago | (#5395462)

Don't they suck? I've had to use one of those pieces of crap for months, 1.8GHz but it's slower than my Athlon 1.2.

The sound hardware is the worst piece of semi-developed-lowest-overseas-bidder junk I've ever seen. The static noises never go away, and you hear everything the CPU and hard drive ever do. Turning up the volume only amplifies the noise.

Makes it worthless for listening to any music. But then, I guess Compaq figures people shouldn't be listening to music at work.

Try google (1, Flamebait)

Ask Google! (652805) | more than 11 years ago | (#5394524)

Just a friendly suggestion [] .

Singing Capacitors (2, Informative)

Anonymous Coward | more than 11 years ago | (#5394533)

When capacitors are charged and drained quickly, they can emit sound. As the charge changes, the two plates that hold the charge will try and move closer or further apart, in a similar way to a speaker. Unlike SRAM, DRAM is actually made from banks of tiny capacitors. In older machines, you could often hear the memory singing while the bootup memory check was in progress.
While you can't hear a bit changing here and there, when changing large amounts of memory very quickly, such as changing/redrawing a screen, the sound soon mounts up, and you can hear it.


Been there, done that. (1)

Zaffle (13798) | more than 11 years ago | (#5394724)

I've had a similar issue with a few systems, in my experience its been the sound cards at fault. My main workstation had an embedded audio card, (I figured I didn't need that good sound), however when I moved my *mouse*, I could hear it out the speakers when they were turned up. When I connected the output of the MB to my stereo, it got even worse. I disabled the internal audio card, and replaced it with a cheap PCI one, and it fixed most of the issues.

I'd suspect the same sort of issue with laptops, since they usually have embedded speakers, you may find the same interference.

You mention when all speakers are removed from the room, you can still hear the noise. I would suggest using a stethoscope to locate the source of the noise. (Your ear may work, but ears are notoriously bad at locating certain types of sounds, the same type I suspect you are hearing). It is almost definatly comming from the monitor, at which point I'd assume its due to the HV circuitry. If this is the case, try changing the video refresh rates, and see if there is any other change. Also note what changes creating the noise. Eg if you create a white box on a black background, does the noise appear, maybe only when moving the white box?, etc.

Treat this like a physics experiement, assume nothing, and test, then retest basic hypothys: "Ok it happens when I move this window, so now if I reduce what I'm doing to the simplest test, eg a black box on a white screen, does it still happen?".

If, in the unlikey event, its not comming from your monitor, check your PC speaker, it may be picking up the noise... maybe.

Could be the power supply (2, Interesting)

Gordonjcp (186804) | more than 11 years ago | (#5394741)

When you do stuff, the CPU draws more current. This could affect all the chokes and stuff in the power supply. Small chopper PSUs such as those used to regulate down the 5v/3.3v rail to the 1.5~odd volts that modern CPUs need have several inductors, which could vibrate and make noises. Especially when attached to a big wobbly fibreglass sounding board.

Charge! (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#5394797)

Anybody notice some ATM's play "Charge" (the bugle call) as they dispense money? (The mechanism coincidentally hums in the proper pitch and rhythm.)

Crappy hardware (3, Interesting)

jfunk (33224) | more than 11 years ago | (#5394826)

Properly designed hardware should not do this.

A few weeks ago, I thought my Soyo Dragon motherboard had gone flaky because I was getting massive fs corruption when copying between drives. I panicked and went out and bought a new motherboard without having done any research. I told the guy I wanted to replace a Soyo Dragon and had 5 IDE devices, including 3 7200 RPM drives. The moron gave me an MSI KT3 Ultra2. That is not a replacement for a Dragon. The onboard sound doesn't even have digital audio outputs. I was using the Dragon's SPDIF to connect to my speakers. It sounds very nice.

I tried it out anyway. One thing I noticed right away was that I could hear noise whenever I selected text or moved a window. I took it back (for other reasons as well) and got my money back. The fs corruption was caused by the power supply unable to put out the power so I got a new one.

Right now I'm using the Dragon's analog out and there's no noise at all at any normal volume. If I turn everything up to maximum, I can barely hear something above the fan noise, but if I play something at that level, my ears would hurt.

Re:Crappy hardware (3, Informative)

shepd (155729) | more than 11 years ago | (#5395081)

You got an MSI for a reason.

From my experience, here's what I've found as to why to buy from different motherboard manufacturers:

Soyo: A value board. Lots of stuff crammed on for a good price, or hardly anything on it for a bargain basement price. Not a bad board, but not top notch.

MSI: The die-hard motherboard. Might not be a cadillac, might even have some annoyances, has no luxuries at all (usually), but dammit, they _always_ work, and are reasonably priced.

Asus: The "high-end" motherboard. Just like cars, where more money gets you some bells and whistles, but not always more reliability, Asus motherboards are bought by people trying to show their box is "awesome" because it cost more. If you look past the pricing, quite a good board. Lots of support, too.

ABIT: The ricers mobo. ;-) Designed for overclockers, with the stability overclockers (not sysadmins) expect. Usually the higher cost for these boards nullifies overclocking benefits, but just like people who add "Type-R" stickers to their cars, the people buying these boards don't care.

PC Chips (aka any weird Chinese name you can think of): When cheap-enough (Soyo) isn't. Zero support, stolen/fake parts, and a high failure rate. But look at those prices! Often found in low-end Brand Name machines.

ECS: PC Chips "top-notch" line. A well supported stolen/fake parts brand motherboard.

A-Open: Overall, pretty good stuff. Good in most categories (price, support, quality, performance) but fell out of favour with after providing me with a broken BIOS for an old board, ruining it (didn't have an EEPROM burner at the time). Definately not an overclocker's board.

Shuttle: Haven't had enough experience with their product. Boards I have seen were reasonable.

Tyan: Haven't seen too many of these boards, but people I know tend to regard them as a good for a frankenserver board.

There's others (gigabyte, biostar [pc chips?], intel, DTK, etc) but I simply don't see these boards in operation much anymore.

So that's why they sold you MSI. You came in telling them your board was causing you hell, so they gave you the bulletproof one. I'd have reccomended you to stick with it and buy a PCI sound card (heck, if it were my store, I'd probably just give you a used SB PCI128), but hey, that's just me. Then again, I'd have replaced your board with an MSI with the Nforce2 chipset, so you'd have decent sound to start with.

Re:Crappy hardware (1)

Halvard (102061) | more than 11 years ago | (#5395408)

Having worked at a Tier 2 distributor, I can tell you that any manufacturer has a bad run. The boards from 10 years experience in distribution and retail that have consistently the best for desktops are Gigabyte, ASUS and Intel for price and reliability.

My opinion is that MSI, Biostar, and PC Chips plus a few others are bottom of the barrel. As the previous poster said, if it's got a wierd name, it's probably PC Chips hiding out (hmm, how come there's a sticker on the chipset? :-) )I don't know about currently, but my recollection is that historically, Acer products from the AOpen line, not the chipset (ALI is Acer Labs Inc.), have a high failure rate. Gigabyte doesn't have the price point of ASUS or Intel but you really are only talking about a couple of bucks. Gigabyte's US office was always helpful on problems (we directly received product from Gigabyte's US operation). Probably easier to work with than any Tier 1 distributor or manufacturer.

The previous post is accurate about price: you pay more and get better reliability. Some people might buy ASUS to brag to their friends, but buying Gigabyte, ASUS or Intel generally adds up to a good investment assuming you are using substandard powersupplies, input power, etc.

Monitor Cable Shielding (2, Insightful)

GrendelWraith (20481) | more than 11 years ago | (#5395054)

Plugging in your monitor to your PC turns it's cable into a giant antennae. Just like TEMPEST. When a bunch of changes are made on screen the signal going to the monitor fluxuates dramatically. This fluctuaion is picked up by the antennae that is your speaker leads.

RF shielding and those magnetic cylinders on the cable help to reduce this.

However you still have an energized cable with radiply changing frequencies flowing across it. And those frequencies radiate and are picked up by other antennae and transmitted along their length.

Have fun sometime and put your cellphone next to a boombox with the volumed cranked up on a dead source. Then call the phone and listen to the funkiness.

iMac too! (2, Interesting)

gabe (6734) | more than 11 years ago | (#5395140)

I have the same problem with my LCD iMac. It's not attributable to simple CPU usage, but rather the interface. When I drag windows, move scroll bars, access menus, etc., I hear a slight grinding sound (sort of like a hard drive but considerably quieter).

Then again, when I've got iTunes blaring it doesn't really matter.

Inverter. (2, Insightful)

ahknight (128958) | more than 11 years ago | (#5395212)

On that laptop there's a power inverter board right near the back of the unit, near the built-in speakers. If that unit is not performing correctly then the power change needed to actually change the million pixels on the LCD will cause a fluctuation in the EMF it emits. Being so close to the BUILT-IN speakers, you'll likely hear the buzz there even if the sound is turned off as the EMF itself is driving the speakers.

Does the sound change when the brightness is turned down? If the above is right, then the sound will not be as loud when the brightness is turned to one notch above off.

Not a machine but... (1)

simong (32944) | more than 11 years ago | (#5395230)

I have a Belkin WiFi gateway through which my half a dozen machines talk. If I control a remote machine using VNC a screen redraw causes the gateway to make quite a pronounced rustling sound as if you can hear the packets going through it.

RF noise (2, Interesting)

halfelf (646037) | more than 11 years ago | (#5395307)

My vote is for the RF noise being picked up by the unshielded soundcard. Just think --- the companies making the cards are constantly trying to find ways to make them cheaper. I mean, just how far can they go adding new features before the average person can't tell the difference anymore. The only thing left at that point is to find ways to make your product more cheaply than any of your competitors, and one way to do that is to not bother with the engineering involved in making an RF shielded card... "Hate my people? I love my people! PULL!"

Did you try... (1)

maxbang (598632) | more than 11 years ago | (#5395332)

turning off your microphone? Worked like a charm for me.

the speakers make a difference (1)

jpsst34 (582349) | more than 11 years ago | (#5395348)

As for what causes this, I am at a loss. But I have noticed that it is very pronounced in my cheap $8 headphones, while unnoticeable in a pair of higher quality. I also cannot hear it when using decent speakers, though I can when using cheap ones. But using the cheap headphones or speakers with a walkman-type device or stereo does not induce the noise, only when connected to my computer.

An interesting test would be... Take the offending speakers or headphones and connect them to your walkman/cd player/ipod/whatever and sit at your computer. Do you hear the noise? If not, and if it only occurs when the speakers/headphones are connected to the computer, then the noise may be internal to the system, the problem occuring at the soundcard, and better speakers/headphones filter it out.

Televisions (1)

Malc (1751) | more than 11 years ago | (#5395413)

I've noticed since I was young that television screens also make noises. Particularly when going from black to suddenly bright.

I have this, and it is real! (1)

scorp1us (235526) | more than 11 years ago | (#5395449)

I have a gateway ev700 monitor, and it does it. This is also the first monitor of mine to ever do it.

When I minimize this window, the first time it makes a noise like a poof, that is just like a small, quiet version of turning a TV off going into power save mode. The window has to be up a while - it only does it once in a while, and never happens in fast repeated minimize-restore successions.

Incedetally, the monitor is mostly white (/.'s color scheme) and gets filled with win98's default green when I minimize. I think the difference in colors is key...

Wow!!!! (4, Informative)

FreeLinux (555387) | more than 11 years ago | (#5395468)

I'm amazed at the number of answers from the "Slashdot experts" and yet I don't see the correct one yet.

The noise you hear is actually fairly simple to explain. First of all, people should realize that this is not RF noise coming through the speaker, as you tried to explain. This is a noise generated by the vibration of a system component.

Your graphics card is the culprit. Remember that your hardware is full of clocks(vibrating crystals) and switches(transistors). These microscopic components move or vibrate at very high frequencies. Vibration creates noise, as we all know. But, the vibrations(or frequencies) change when the image on the screen changes. Certain colors and certain movements on the screen create frequecies that are perceptible to human hearing and you hear a slight buzz or high pitched whine form your video card.

If you want to test my answer, try changing the frequencies for your display and you will hear the sound come and go. You will also notice the pitch will change when different frequency setting are used.

Some hardware is less prone to this because of thicker cladding or more secure mountings but, they all do it. It's just that some equipment is louder than others.

transformer windings (1)

TheGratefulNet (143330) | more than 11 years ago | (#5395605)

usually in dc-dc converters there are transformers. and those windings will hum when a load is put thru them.

for an lcd (at least) you need a big step-up voltage to drive the backlight. on my dell laptop I hear noise near the keyboard area and I think its due to a dc-dc converter showing some signs of age (it didn't make much noise when it was brand new).

If you... (4, Funny)

psyconaut (228947) | more than 11 years ago | (#5395669)

...bury you TiBook in the forest and leave it there....does it still make screen redraw noises? ;-)

Would someone read the post please? (0)

Anonymous Coward | more than 11 years ago | (#5395828)

If one more person mentions the sound card I'm going to scream. READ THE POST! He disconnected his speaker, gone, killed it, no speakers at all!
Now that we know it is physically impossible for the SOUND CARD to generate the sound then we can look in other areas.

I have also noticed this event in all my PC's. I have always attributed it to the fact that the monitor is changing how the guns work, however as it seems to also happen with LCDs I'd have to agree with the capacitor posts.

Do you get the same sound with the monitor turned off? If not then it is the monitor. If it is still there then its most likely a result of the capacitors. Could there be 2 distinct noises? 1 from the monitor and 1 from the capacitors?

Another thought, try using a smaller font. :P

well... (1)

silicon1 (324608) | more than 11 years ago | (#5395937)

I know when I turn off the external speakers on my stereo and unplug my headphones from it, turn up the volume all the way on my stereo system; I can hear the music coming from the amplifier without any speakers, maybe this is related?

Not necessarily just the hardware (1)

Glass of Water (537481) | more than 11 years ago | (#5396028)

I have this problem with my Dell Latitude c600's LCD. Under windows, I get the quiet grinding noize mentioned by some earlier posts whenever moving smething on the screen.

However, on RH 8.0, using X windows or without, the screen emits a fairly loud buzz that only goes away when something on the screen is moving.

I don't know if I have especially good ears. I suspect I don't, but this buzz is maddening.

So the point is, you might be able to attribute some of the noise your monitor makes to the driver, the refresh rate (though changing it hasn't worked for me) or some factor of the driver.

TV and Movies (1)

huh_ (53063) | more than 11 years ago | (#5396098)

Just be thankful its not as loud as on TV or in movies. The screen beeps or makes some kind of noise for everything.
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