@pangolin12 I can't remember having heard any loud music being played from nearby structures, but maybe they sometimes do. Pairi Daiza does play some classical and "ethnic" music in different around the park, but in my opinion the level was never disturbingly high - and I don't remember hearing any music in the Australian aviary.
In fact the only noise disturbance I experienced in the aviary came from the eclectus parrots.
That said, I'm sure large crowds might be just as disturbing to the birds and there's not much that can be done about that.
@KevinB when I visited the refreshments building opposite the train station had a stand where live music was being played. It was so loud I could very faintly hear it in the kingdom of Ganesha! I thought the classical music was a bit excessive in the Middle Kingdom and other areas- especially the crypt
@pangolin12 There was no live music being played there when I visited, luckily. I would say having loud music played isn't the best policy from Pairi Daiza. That said, I didn't find the music excessive necessarily and it didn't bother me anywhere, so maybe the volume was lower when I visited than when you were there. I can't remember there being any music in the crypt, actually.