If you have not noticed, or switched to the new Yahoo! Mail Beta yet, Yahoo has integrated their Messenger (chat) to Yahoo Mail. Yahoo has just begun to roll it out to all users. When it becomes available to you for the first time, you will notice pop ups pointing to the new Messenger icons.

One feature of the integrated Yahoo! Messenger is sound notification. When a new chat message is received, you will hear a "bursting bubble" sound. Unfortunately, you can’t change the sound but you can disable it.

To disable, go to Options and select Mail Options:

In the General section for Chat sound alerts:, deselect Play a sound when a new chat message is received.

Now you will be able to chat with your friends in peace!