There's been some recent talks about ambience noises in the orchestra hall, I decided to take this seriously and make my own library .I tried to capture as best I can the hall noises during an orchestra rehearsal. For this I attended several rehearsals, kept a watchful ear on any noise going on, the result is quite stunning. As an example I'm using one of my own pieces, an excerpt of Sadness of Sauron.
The first version which you should listen first is without the ambience noises, the 2nd is with the ambience noises.
Without ambience: http://www.guybacos.com/audio/1.mp3