In the outdoor theatre at Epidavros, you can sit at the top and hear an actor (ok, a guide, these days) drop a coin, light a match, or breathe deeply, a hundred metres away. What’s the deal? …And why can’t we get that sound now, when we’re better at calculating things and have better materials and everything?
It does look quite a bit like a speaker, or possibly a satellite dish - if the speaker similarity has anything to do with it I don’t know, but the dish is shaped that way to reflect everything toward the centre - or, for broadcasting, with the same antenna: From the centre (the actor) toward the dish (with the audience) and out. I don’t know what interference and reflections would mean here…
We tend to have the audience much steeper now, both to use less expensive space and to get them closer to the stage - how great an effect does that have?
Nowadays, of course, amplification is cheap and easy, and sometimes you want it, if you’re playing Jesus Christ Superstar or something, and then the drums would be the limiting factor (everything else could be turned down) and those alone would probably kill half the audience in Epidauros.
(Posted this here rather than Cafe to potentially pick up more people who know about acoustics, interference, satellite dishes and so on.)