Why is it when i use facebook chat and i get a new chat message the

[.•°?Rae Rae?.•.™]

"popping" sound cannot be heard? And instead of the popping sound not being heard when i am chatting with two friends at once and one friend sends a message the chat conversation does not let me type and letters do not appear on my second friends chat until the message from the one friend is fully sent. What is causing this? How can i fix this?