She always pushes me out. I went to the girl at the top of the bridge and she gave me Sitrus Berries. Is there any way to enter the room without being pushed out? Do you need Meloetta or something?
No, the girl who gave you sitrus berries are wondering where to mysterious voice is coming from, and once you find that girl who pushes you out, she gives you a reward. There isn't any way to enter the room who pushes you out.
[Source][1]
Hope this helps! [1]: http://bulbapedia.bulbagarden.net/wiki/Village_Bridge#Secret_singing_area