These days, there's a lot of performances that are loudspeaker arrays.
Indeed and very occasionally it’s speaker arrays where audiences are completely unaware it’s a speaker array (or partially a speaker array)! Some concert halls have sophisticated electronic enhancement. Hidden mics picking up the acoustics nearer the stage, amplified and pumped out of hidden speakers nearer the back of the auditorium, with some enhancement from from EQ and even reverb units (with custom algorithms for that particular venue). It’s pretty subtle and no one is aware of it but if you turn it on/off during rehearsals you can clearly hear the difference in the auditorium and IME, it does work/help. Kind of makes a nonsense of purists claims of “natural”, “real” and no processing/mixing on the recording.
One thing that's foreign to us is the standing crowd in back as walk ins …
Not usual but not uncommon here in Europe. Some/Many concerts and particularly with opera and ballet, ticket prices were very high. Effectively limiting them to just royalty and the aristocracy in the first half of C17th and earlier. Then the Industrial Revolution started to have an effect, a new class of wealthy industrialists emerged who wanted what the aristocracy had and, a new “upper” working class. People with limited working hours (and therefore leisure time), such as supervisors and management, who were not really rich but had disposable income. So concert halls started to be built outside of royal palaces and music composition changed (to be more pleasing/entertaining), the classical music period was born and then the Romantic period (even more entertaining), to accommodate the explosion of those with disposable income. Everything got bigger during these times but so did the costs of larger orchestras and building/operating the concert venues. So they took advantage of this market by opening up those least desirable areas of the auditorium to more of the general public, above the top row of boxes in Opera Houses and at the back of the auditorium for example, where the sound was very poor, the view was terrible but the ticket prices more affordable. This wasn’t such a “thing” in places like the USA, which didn’t have such a history or class structure and where those buying the cheaper seats still expected to get a moderate view/sound. For example, as a poor student, up in “the gods” at the Royal Albert Hall, you simply couldn’t hear any music in some of the quieter passages. The RAH, is ridiculously big though.
… wonder if back then they did actually try to deaden the sound for reason to pay for seats.
No, not that I’ve ever seen and acoustically I can’t see how it would work. “Deadening the sound” requires absorption (absorption of acoustic energy), you get cleaner/clearer sound but a lot less volume. In the opera houses and bigger concert halls the reality of the choice would be between unclear sound (with too much reverb) or little/no audible sound at all, so not much of a choice.
The situation isn’t quite so clear cut though. Most traditional orchestral instruments need a fair amount of reverb but this isn’t the case with theatres/playhouses where those same levels of reverb would destroy the intelligibility of speech. So too much reverb is just as bad as no sound at all and theatres/playhouses are much deader than concert halls (and the performers just have to speak louder). There’s speech in operas too though and a certain amount of intelligibility is desirable with the lyrics, so Opera Houses tend to be quite a bit dryer than concert halls, although not (as far as I know) by using absorption panels per se but mostly by just not using as much deliberately reflective surfaces as concert halls. With more modern amplified performances, drier is also better. So with multi-purpose venues we’ve got highly conflicting requirements, hence why some modern concert halls have adjustable acoustics and/or electronic systems.
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EDIT: I should mention that the use of drapes is common in opera houses (and has been for a couple of centuries or so) and they are of course fairly absorbing. Also that electronic concert venue acoustic enhancement (using reverbs, etc.) goes back to the 1980’s and such systems are/can be retrofitted to even C19th opera houses/concert halls. That’s often not public knowledge though, in some instances it’s very hush-hush and not even the artists/performers know!
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