I never understood the rage against voicespamming. I only hate that a textual representation clutters up the chat, but the actual audio? Doesn't bother me, even if 10 guys are spamming "CHARGE" all the time.
I'm not sure if a cooldown would work, because 10 guys spamming still means cacophony with a 5 sec delay. It's worth a try, though. Maybe it should only kick in after the third voice command, or whistling should be excluded, or something.