Q. This beep sound is annoying under Linux, how do I disable it forever?

A. To be frank there are many ways exists - to turn off terminal beep. Use any one of the following method as per your requirements.
If you are using Gnome terminal

a) Open Gnome terminal
b) Click on Settings > Preferences > Silence Terminal Bell

Or Click on General Tab -> General -> Un-Check Terminal bell option
If you are using xterm

Open ~/.xsession file (i.e. /home/you/.xession)
$ cd
$ vi .xession
Append following line
xset b off

Save and close the file.
If you are using bash

Open you ~/.inputrc file (i.e. /home/you/.inputrc file
$ cd
$ vi .inputrc
Append following line:
set bell-style none

Save and close the file.

If you just want to turn off beep for VIM text editor:
Open vim config file ~/.vimrc (i.e. /home/you/.vimrc)
$ cd
$ Vi .vimrc

Append following line
set vb

Save and close the file.
If you are using Ubuntu Linux

a) Click on Applications > Accessories > Terminal
b) Now click on Edit Menu > Current Profile
c) Click on General Tab > General > Remove check box (Terminal bell)
引用自：http://www.cyberciti.biz/faq/how-to-linux-disable-or-turn-off-beep-sound-for-terminal/

个人经验：
redhat9 的beep在 “start”->"preferences"->"keyboard"->"sound"