The lenovo S series netbooks can get pretty annoying with the speaker beeping all the time. To disable the speaker beep while plugging and removing the charger, you can change the setting in the BIOS. If there is no option, you must upgrade the BIOS.
Other annoying beep sound when I shut down my Ubuntu. To get rid of this I blacklisted my pc speaker:
gedit /etc/modprobe.d/blacklist
add line
blacklist pcspkr
Save and reboot.
