It seems pretty short-sighted to blame it on actors. They are a low-level cog in the machine that are trained to exactly what they are told. It's the job of the

It seems pretty short-sighted to blame it on actors. They are a low-level cog in the machine that are trained to exactly what they are told. It's the job of the director to get the performance out of them that will look good on screen. Can't the sound teams talk to them? Seems much more likely that, as other posters have said, movies are edited to play on the big screen at high volume.