Hi,
I am very sorry for the experience you currently have in your new place,
In my opinion, this is an absolutely inappropriate behavior and I think the only way to stop it is to report such behavior to the accommodation reception.
Please, do not be afraid to speak to your flatmates about this as they really should listen to you, as what they are doing is quite immature and they are lacking consideration to others.
University is the beginning of an adult life, and adult life implies responsibility for the actions person makes. I had the same situation when I first moved in to my accommodation. The only thing that I really advice you to have in mind is that you are right. It is really essential to communicate with your flatmates at the beginning of your year as it then could transform into a habit and they may see it as something you can constantly tolerate.
I would first try to speak to your flatmates and express how you feel about the situation. If they do not listen to you, please do not confront them, but go to the reception or make a noise complaint in an app. The noise complaint is anonymous and stuff will never tell them who reported the noise.
Once again, I am very sorry for the experience you currently have in your new place, feel free to respond to this message if you need any further support
- Ilya