How to disable sound when error occurs

[Wang, Zhu]

I am frustrated by a probably very simple problem:

Whenever I made a mistake, e.g., scroll up the mouse using the middle wheel 
when the pointer is at the beginning of buffer, some sound arises. But I don't 
need it to bother me. How can I disable it? After I did some search and looked 
at help files, I still have no clue.

Thanks for any help.

Zhu Wang

Southern Methodist University