How to disable the warning sound "beep, beep"
 

When I have some not probably action such as move the cursor to the VI screen boundary or some errors happened, there is a sound "beep" to warn you. That is so annoying, how to disable it? Thank you.

I don't know if it will work in slack, but in my debian sure it does. It's worth a try:
http://www.debian-administration.org/articles/110