Some people like to have a sound play every time they get a new message on Facebook Chat, or any other IM or email program for that matter. Some don't want their computer making noises all day long. This is certainly a personal choice and one that Facebook Chat lets you have.
You can easily toggle your message notification option on Facebook Chat. Just click on the chat menu and then click on the settings link in the pop up bar. Where you see the option that says "Play Sound for New Messages" you can either click it on or off.
>What Is Facebook Chat?
>Start a Conversation Using Facebook Chat
>Smileys and Emoticons for Facebook Chat
>Delete Your Facebook Chat History