Somehow you can upload videos with sound to 4chan. I did that like a month ago, but I can't remember how. Someone remind me pls.
If you're perhaps referring to the old ways of embedding a sound clip into an image and being able to play it from there, they've removed that a while ago.
You're probably talking about webm's with sound, which are only allowed in >>>/gif/ and >>>/wsg/.
In my opinion, I believe Hiro should give /wsr/ webms with sound so people can request the track in a webm.
