[linux-audio-user] X events making noise through soundcard.

Gian Paolo Mureddu gmureddu at prodigy.net.mx
Thu Jul 27 04:35:34 EDT 2006


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Hi everyone!

I have noticed this for a long time, but did not actually thought
about it until recently. It so happens that apparently a lot of X
events produce some sort of noise ranging also from what I am doing.
First of all, here are my system's specs:

* AMD Athlon 2800+ (S754)
* VIA-based motherboard with K8TMM chipset. VIA VT8235 southbridge
(the box says VT8237R, but it actually is a VT8235)
* 2x 512Mb RAM DIMM sticks DDR PC-2700
* 2x 80 Gb ATA-100 HDDs; one Western Digital, one Seagate. Attached to
primary IDE channel.
* 1x 40 Gb ATA-133 Maxtor HDD, connected through add-on IDE card.
* 1x 10 Gb ATA-66/100 Seagate HDD (used mainly for storing .ogg
files), connected through the IDE add-on card
* 1x LG CD-RW 52x32x52, secondary IDE master.
* 1x LG 16x DVD-RW , secondary IDE slave.
* 1x generic brand Floppy disk drive.
* 1x GeForce 5900, 128Mb VRAM. Using nVidia's proprietary driver.
* 1x Sound Blaster Live! Value, the primary sound card. Using ALSA
1.0.11 emu10k1 driver... This has been my trusty sound card for so
many years now.

So this noise happens whenever there are events, from dragging the
mouse, to cliking on windows, to scrolling a window or even typing
some text. The noise is not very audible, only if I crank the volume
really high, and it is composed primarily of low frequency sounds.
These noises even vary from application to application. They're like
clicks in Thunderbird, with a rather low repetition frequency, and a
much more rapid succession in Firefox, for instance. When changing
focus of windows, or when changing from one virtual desktop with some
windows to another (despite if the other has or no windows) the sound
I can only describe it as "similar to that sound in Diablo II when you
changed tabs or clicked the close button of any other "window", like
the Inventory"... I can't really describe it better than that. I will
try to see if I can record some these sounds. There's a "base humming"
sound in the background if I crank all the way up the volume either on
my speakers or headphones.

Anyway, my question is what are these, and why are these produced? I
know they respond to activity in the computer, mainly from X, or the
video card, but why?

Another thing that I think I read somewhere a while back. I have
optical drives connected to the sound card through analog cables... Is
it possible that these are working as "antennas" and what I hear is
actually the the activity of the PSU/CPU/Memroy, etc?
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