On 0, "H. S. Teoh" <hsteoh@quickfur.yi.org> wrote:
> [Please Cc: replies to me, I'm not subscribed due to high volume.]
>
> Recently, I noticed this very odd phenomenon with my sound card. I'm
> using an SB16 with the OSS drivers, and there is this persistent
> background static hum, which is noticeably loud on my headphones. This hum
> also has buzzes which coincides with hard drive accesses and mouse
> movements. At first I thought it was due to bad hardware, or perhaps
> broken/incompatible sound drivers; but one day, I got an idea and ran the
> following program:
>
> #include <unistd.h>
> void main() {
> nice(19);
> for(;;);
> }
>
> I ran the program in the background, basically to eat up all idle CPU
> cycles. Amazingly, when this program is running, the static hum
> disappears. When I kill it, the hum returns.
>
> Does anyone have any idea what might be causing this? I suspect it might
> be something in the kernel idle loop that's causing this; but I've looked
> over my kernel config several times and can't see any option that might
> affect this.
>
> I'm using kernel 2.4.18 currently; the problem happens on both 2.4.16 and
> 2.4.18.
>
> Any ideas/suggestions would be appreciated. Thanks.
This sounds a lot like electromagnetic interference. This will not be
caused by a software problem. Possibly the chassis of your case is
not earthed properly, or your motherboard was not made with
electromagnetic compatibility in mind. About all I can suggest is
moving your SB card to another slot and seeing if that helps.
Tom
--
Tom Cook
Information Technology Services, The University of Adelaide
"That you're not paranoid does not mean they're not out to get you."
- Robert Waldner
Get my GPG public key: https://pinky.its.adelaide.edu.au/tom.cook-at-adelaide.edu.au
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