Yea this one is a little more complicated, it will be in the next update but if you want it now-
Create this function anywhere in the init python block at the top (will reply to this with a copy paste):

(The vars in using here I've just added to config and done = "thesoundfile")
Run the function in these 3 places:
1-

2-

3-

That should do it :)
(Also, add "code" with the image and video, so it doesn't play a sound when code executes)
I haven't decided how im going to handle image messages yet, but you can just change the 'return' there to a custom 'sent image message' sound if you want. Or if you've only ever going to be receiving images just set it to the received sound.