When I explored this compound years ago, it was in dosages ranging from 40 mg to 80 mg. In my opinion, it's possible to have reasonable communicative conversations. You yourself sound weird because you try to overcompensate your own perception of your voice as having dropped in pitch (and in general the non-linear change in pitch almost all sounds affected get), but people can understand you. Understanding other people is generally no problem, but how well things will go seems heavily dependendent on things like level of redundancy (I've had experiencies of speaking over the phone where it was almost impossible to decipher what my friend on the other side of the line was saying, something which ended up with me instructing him to "right, now, just say goooooogle, slowly. OK? Gooooogle. Now say it.", and only getting this garbled oouououo sound back) and gender (male voices, which tend to be deeper, tended to suffer more heavily from the exponential drop in pitch, making them harder for me to fathom).
IMHO music is more likely to be reducded to "one big mess of sounds", and often quite sounding metallic and "off". After the novelty factor wore off, I kept to listen exclusively to percussive types of music only if I really had to listen to music on DiPT.
