So… if passengers can’t understand the announcement due to low volume, is that something that would keep the plane grounded until maintenance has fixed it? On the one hand, announcements can be a safety issue, but deaf passengers and those who don’t understand English aren’t prohibited from flying without an interpreter.

In any case, there are so many knobs (physical or virtual on a screen) in the cockpit and even the FA station, why did Boeing choose to not let crew adjust the volume?