====== PC Speaker ======
<WRAP round info>
This might no longer be an issue, at least I have no longer heard a PC speaker emulation in modern notebooks. However, I will leave this here for your information as it will still work in case it is needed.
</WRAP>

Especially on notebooks the PC Speaker can be very noisy and thus annoying. This is because notebooks don't have a real speaker and to emulate one, the output is instead being sent to the sound card.

So you might want to disable the PC Speaker, but that's not as easy as it might seem. The following led to success on all systems I had to silence until now.

As root, enter the following commands. This disables loading the PC Speaker kernel modules.

  echo "blacklist pcspkr" >> /etc/modprobe.d/blacklist.conf
  echo "blacklist snd-pcsp" >> /etc/modprobe.d/blacklist.conf

Afterwards, reboot your system. However, on some systems this is not enough. There you need to use a mixer (e.g. "alsamixer") and mute the channel "PC Speaker" as well. This depends on your sound card.

Enjoy the silence!