Ok - It can’t just be me - What causes that hum/buzzing that I can definitely hear (but only sometimes) when text is displayed on a screen? It happened with old style CRT televisions eg when “teletext” ( a UK text news/information service) was displayed years ago - It still happens occasionally on my TFT computer screen - and happened sometimes with my old CRT PC monitors.
I know PC monitors often have a frequency reported as part of the specs but beyond that not sure if it’s relevant - why does text appearing on the screen cause the sound but not all the time?
Ah right thanks, now I at least know what it’s called - I assume then it emanates from the speaker and not the screen itself in some way- it’s kinda hard to tell though and playing with the volume control doesn’t seem to affect it.
On a CRT monitor, the sound is probably not coming from any components intended to make sound (i.e. speakers), but rather from the components that generate, or handle the scanning - they’re working with electrical signals oscillating at high frequencies, and squirting them through transformers which are essentially electromagnets - it’s almost inevitable that under circumstances like that, something will start to vibrate - and it’s the vibration that turns into sound.
On a flat screen LCD monitor, I can’t say I’ve ever heard anything similar, but if you have, it might be either some kind of leakage from one of the conductors in the VGA cable to the speakers, or some other kind of interference to the speakers (i.e. not actually caused by the VDU), or it could be the driver circuit for the fluorescent backlight (although I wouldn’t expect that to fluctuate when the picture changes).
I think gotpasswords and Mangetout are talking about different phenomena. And I think gotpasswords is talking about the right one, in terms of the OP’s question. Which should result in sound coming out of the speakers, not the monitor directly, as a result of the video signal “leaking” into the audio signal, unless I misunderstand something.
Maybe this is the question I have been wanting to ask but didn’t know how to describe it. I’m running a Mac G5 but using a Dell monitor. Sometimes I get an electronic noise out of the speakers that is really annoying. It almost sounds like an electronic horse galloping and then stopping. Weird and annoying. If music is being recorded at the time the recording will pick it up.
What steps should I take to resolve the problem? New cables? New monitor? Is there a software problem? Learn to live with it? I’m open to any ideas. Thanks.
That’s most likely your problem. Cellphones “check in” with their base stations from time to time and the interference makes a distinctive “duh-dudu-duh-dudu-duh” sound. You’ll also get a similar, but longer, sound when a text message is coming through. If I have my cellphone on the desk by the computer speakers, I can hear it and pick up the phone before the text-message bleep even sounds. If you have a call coming in, you’ll get a more continuous buzzing interference for a second or two before the phone starts ringing.