Not nearly self-aware enough, if you were to go around saying such things to people in person. What a shocking insult, to tell someone their very voice sounds unhuman! I can't say you should never, of course, but I would hope very much you reserve such calumny only for when it has been thoroughly earned.

But of course this is only a website, where there are in any case no drinks of any sort to go flying for any reason, and where such an ill-considered thing to say can receive a more reasoned response like this, instead.