[kilnr]

How does this impact large orchestras? Some of these musicians have got to be (way) over 10 m apart. Even 10 m at the speed of sound is almost 30 ms.

[saberdancer]

That is the role of a conductor. He hears the piece as it should be heard and is active participant in "tuning" it. My understanding is that he can slow down/speed up various performers to get them in sync.

Performers need to learn to ignore the rest and play their instrument while looking at the conductor.

[pishpash]

That's why they rely on light in addition to sound: watching the conductor, watching each other.