For “our voices are gone,” you can go with as little as 声がない (koe ga nai, “there is no voice”), and since Japanese is all about implication you don’t necessarily need to go further than that.  There’s a few ways to imply completion and unfortunateness in Japanese verb conjugation, but I’m fairly sure they don’t work well with non-active verbs, so it might be best to keep it simple.

EDIT: You can add some emphasis to the end, if you want, with particles like さ (sa - emphasis, but really informal) or よ (yo - emphasis, implying the revelation of new information to the listener).  の (no) can also be used as a sort of softer emphasis at the end (and is generally considered more feminine than さ or よ, at least in that regard), but can also either imply a question or be used outright as an informal question mark.