Whisper notification

[dmentia777]

I cannot seem to find an add on that will play a sound when I receive a whisper message. I'd like to see something benign (a quiet ding! would suffice) that will notify me with a sound the same way the native UI does when I receive mail. I often miss whispers because I've got my eyes fixed on some fight or have another window open obscuring chat. Does this add-on already exist?