Portuguese to English Art/Literary Music Performance, theatre

From a text describing the structure of a performance/installation:

"As mesmas cadeiras, em número igual ao dos músicos em cena, são dispostas informalmente dentro do círculo, obedecendo a sua posição, que não é permanente, aos sons e às suas condições de propagação."

The chairs referred to are the same that the audience sit on in a circle.

I have found "propagation conditions", particularly with reference to radio. It sounds rather technical in English, I am unsure whether a literal translation is best here. I understand it to mean something like the way each sound is transmitted in the room - I would struggle to get that meaning from propagation conditions I think.

All help appreciated.