This tutorial describes how to disable the pcspkr beeping - stops login screen beep (x1) and logout/shutdown/restart beeps (x2).

A. Stop the pcspkr module from loading:

1. In the Terminal (re)move /etc/modprobe.conf, if present, as it supersedes anything in /etc/modprobe.d/* (unless you add include /etc/modprobe.d).
2. In the Terminal create a file /etc/modprobe.d/pcspkr.conf containing: blacklist pcspkr
3. In the Terminal type: su
4. This gets you a login on the Terminal as root (you'll need to authenticate).
5. In the terminal type: depmod -ae
6. Ignore any warnings.
7. In the Terminal type: update-initramfs -u
8. In the Terminal type: exit
9. This puts you back at the Terminal prompt as the original user.

B. Configure Alsamixer:

1. In the Terminal type: alsamixer
2. Press [F5] to list all audio channels.
3. Look for a channel called 'Beep'. If there isn't one try selecting a different sound card by pressing [F6].
4. Once you have found 'Beep', highlight it and lower the volume to the bottom. Then press the [M] key on your keyboard to mute it. 'MM' should now have appeared in the square under the volume scale.
5. Press [ESC] to exit from Alsamixer.
6. In the Terminal save the Alsamixer changes by typing: sudo alsactl store (authenticating if neccessary).

C. Reboot:

1. Reboot the machine. If everything went well there will be no logout/shutdown/restart beeps heard or login screen beeps when the system comes back up.

I hope this has helped you.