tux@slitaz: nano ~/.xinitrc

# ~/.xinitrc: Executed by slim login manager to startx X session.
# You can use F1 with Slim to chage your window manager or configure
# it permanently with your personnal applications.conf file.
#
. $HOME/.config/slitaz/applications.conf
#Stops the beep:
xset -b
case $1 in

Thanks for the reply, but this doesn't seem to make any difference.

Try appending this line to ~/.inputrc :

set bell-style none

(N.B. I don't seem to have a system beep at all, so can't verify either!)

No joy, alas. Indeed, there was no file '~/.inputrc'. It's not a deal-breaker, this beep, just an itch I can't scratch. ;) Thanks for your help anyway.

j0hv don`t give up. Probably you don`t have xset. Write in xterm
$ which xset
It should return
/usr/bin/xset
When you get nothing. Write as superuser in xterm:
# tazpkg get-install xorg-xset
After installation write in terminal as normal user:
$ xset -b
The bell should disappear. It works for current session only. If you want to turn off this annoying bell for the next session edit ~/.xinitrc as in mojo`s answer. It really works.
If you only want to turn it off in xterm, without other system applications, add to the ~/.Xdefaults file in the section "Xterm settings" the line:
*visualBell: on
Then you will have blinks in terminal instead of bell.
Here is my section Xterm Settings from .Xdefaults file:

! XTerm settings.
!
xterm*background:	black
xterm*foreground:	white
xterm*cursorColor:	#6AA2D8
xterm*scrollBar:	on
xterm*faceName:		DejaVu Sans Mono
xterm*faceSize:		11
 *visualBell:		on

j0hv, you can also start the "alsamixer" in terminal (or from SliTaz main menu) and mute the beep slider or adjust it's volume. It's works for my netbook.

All this methods affect X server. I want to remove the module responsible for PC-speaker, but could not find it among my modules. In other Linux distros the module for PC-speaker is pcspkr or snd-pcsp. In my system is no module with this name. The bootlog shows one message with speaker inside:

input: PC Speaker as /devices/platform/pcspkr/input/input0

Could somebody help me remove PC-speaker module?
Here is my lsmod list:

Module                  Size  Used by    Not tainted
ipv6                  198616  10 
nf_conntrack_ipv4      11580  2 
nf_defrag_ipv4          1492  1 nf_conntrack_ipv4
xt_state                1704  2 
nf_conntrack           50648  2 nf_conntrack_ipv4,xt_state
iptable_filter          2196  1 
ip_tables               9640  1 iptable_filter
snd_cs46xx             70540  1 
gameport                9348  2 snd_cs46xx
snd_rawmidi            16920  1 snd_cs46xx
snd_seq_device          5544  1 snd_rawmidi
snd_ac97_codec         88736  1 snd_cs46xx
ac97_bus                1308  1 snd_ac97_codec
snd_pcm                51780  2 snd_cs46xx,snd_ac97_codec
snd_timer              16344  1 snd_pcm
snd                    43584  8 snd_cs46xx,snd_rawmidi,snd_seq_device,snd_ac97_codec,snd_pcm,snd_timer
soundcore               5180  1 snd
snd_page_alloc          7256  2 snd_cs46xx,snd_pcm
yenta_socket           20988  1 
rsrc_nonstatic          9136  1 yenta_socket
pcmcia_core            27628  2 yenta_socket,rsrc_nonstatic

Gawron, seems like its not module, and hardcoded into kernel. Can you check this?

Thank you Lexeii for answer. Yes I think you are right. Probably the only way to turn it off is kernel compilation. So if this is the only way, I have to give up. My computer is to slow.

There is one way to turn off this bell without touching kernel code. Make a file in your home folder separate for each user ~/.inputrc with this entry inside:
set prefer-visible-bell
You will have screen blinking instead of bell. It works with bash shell. Don't know if it works with default SliTaz sh shell. Tests more then welcome:).
Bell disappears from all the system even the real linux terminal, but still remains on slim login manager.

Great, thanks everyone. :)