Wrong kind of consistency. I'm talking about consistency in the fiction which is far, FAR more important than blindly obeying rules that become borked in situations they aren't meant to handle, so that you can be consistent with the rules. The DMG says this...
"The D&D rules help you and the other players have a good time, but the rules aren't in charge. You're the DM, and you are in charge of the game." When the rules interfere with reasonable outcomes, to the point where you're going to rule that you hear a still wizard that's 30 feet away while 8 giants roar war cries and bang giant metal shields and swords, and their elephant mounts trumpet loudly, the rule should be changed for that circumstance. Blindly obeying the rules in that situation results in an utterly ludicrous result.