Programs causing static noise in speakers?

Question

Does anyone know a reason why my programs could be causing my speakers to output some soft static? The programs themselves don't have a single element that outputs sound to anything, yet when I run a few of my programs I can hear a static coming from my speakers. It even gets louder when I run certain programs. Moving the speakers around doesn't help, so it must be coming from inside the computer.

I'm not sure what other details to put down since this seems very odd. They are OpenGL programs written in C++ with MS Visual C++.

Edit: It seems to be that swapping the framebuffers inside an infinite loop is making the noise, as when I stop swapping I get silence...

Answer 1

Computers consume a different amount of power when executing code. This fluctuation of current acts like a RF transmitter and can be picked up by audio equipment and it will be essentially "decoded" much like a AM modulated signal. As the execution usually does not produce a recognizable signal it sounds like white noise. A good example of audio equippment picking up a RF signal is if you hold your (GSM) cell phone close to an audio amplifier when receiving a call. You most likely will hear a characteristic pumping buzz from the cell phone's transmitter.

Go here to learn more about Electromagnetic compatibility. There are multiple ways a signal can couple into your audio. As you mentioned a power cord to be the source it was most likely magnetic inductive coupling.

Answer 2

:)

You will be surprised to know that the speaker input is picking up static from the hard disk. When you do something memory/disk intensive (like swapping framebuffers) so that the hard disk has to rotate fast, the sound will appear.

I had the same problem some years back, I solved it too. But I am sorry that I don't remember how I did it.

Hope the diagnosis helps in remedying the problem.

UPDATE: I remembered. If you are using Windows, go to volume control and mute all the external inputs/outputs like CD input etc. Just keep the two basic ones.

Answer 3

Since you say you don't touch sound in your programs, I doubt it's your code doing this. Does it occur if you run any other graphics-intensive programs? Also, what happens if you mute various channels in the mixer (sndvol32.exe on 32-bit windows)?

Not knowing anything else I'd venture a guess that it could be related to the fan on your graphics card. If your programs cause the fan to turn on and it's either close to your sound card or the fan's power line crosses an audio cable, it could cause some static. Try moving any audio cables as far as possible from the fan and power cables and see what happens.

It could also be picking up static from a number of other sources, and I wouldn't say it's necessarily unusual. If non-graphics-intensive programs cause this as well, it could be hard-disk access, or even certain frequencies of CPU/power usage being picked up on an audio line like an antenna. You can also try to reduce the number of loops in your audio wires and see if it helps, but no guarantees.

Answer 4

Crappy audio hardware on motherboards, especially the ones that end up in office PCs. The interior of a PC case is full of electrical noise. If that couples to the audio hardware, you'll hear it.

Solution: Get a pair of headphones with a volume control on the cord. Turn the volume on the headphones down, and turn the volume on the PC up full. This will increase the signal level relative to the noise level in most cases.

Answer 5

Most electronic devices give off some kind of electromagnetic interference. Your speakers or sound hardware may be picking up something as simple as the signaling on your video cable or the graphics card itself. Cheap speakers and poorly-protected audio devices tend to be fairly sensitive to this kind of radiation, in my experience.

Answer 6

There is interference on your motherboard that is leaking onto your sound bus.

This is usually because of the quality of your motherboard, or the age of it. Also, the layout of the equipment inside your computer (close together, over lapping) often will make interesting EM fields. My old laptop used to do this a lot easier as it got older.

So as things are winding up or down you'll hear it.

Try to see if it happens on a different computer. Try different computers of different ages and different configurations (external soundcard, or a physical sound card, etc).

Hope that helps.

Answer 7

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