How to turn on sound when I receive messages?

I might be wrong, but I don't think Mingle2 has support for any special "alert" sounds like Facebook has. If you go to your main profile page (your "account" page), there's a link for you to change your account's settings for things like messaging, regional restrictions and forums, but there isn't anything for sounds. The only thing like that is for changing the color of text, but that's about it. And color changing for typed text I think only works in the Forums. I don't think it works for private messages. I haven't used that feature, so I'm not fully positive. Hope that helps.

what a great suggestion.

Turn on sound when receive messages

seems to be it used to have this annoying beep thing that went off anytime someone wanted to instant message ya but that feature is not longer available