What you're experiencing is often referred to as the "audible bell." There are probably many ways to disable this (often annoying) feature.
Perhaps the simplest is to blacklist the
Create a new
modprobe.d configuration file either
blacklisting it (will not load on-boot, but can be loaded at a later time):
# echo "blacklist pcspkr" > /etc/modules.d/bell.conf
installing it to a black hole (will never be loaded unless you remove the file or comment out its contents):
# echo "install pcspkr /dev/null" > /etc/modules.d/bell.conf
bell.conf as an example, it can be named whatever you'd like.
reboot, or manually run the following to get the behavior functional immediately:
# rmmod pcspkr
Doing the above should pretty well ensure that you never get an audible bell again.