How to tell my roommate that her loud singing bothers me?

Hi,

So, my roommate is lovely and everything, but she has this habit of singing out loudly whenever she's revising (she would put on her earphones/headphones and start singing some song). She also loves to make self commentary while she's watching videos and movies on her laptop (eg: "Oh, why would you do something like that, you idiot" etc) . She laughs and gives out emotional cries of horror, tears etc. She does all of this in an erratic manner, like one moment she'll be singing out loud, the next she'll be quiet, and suddenly BAM! she starts belting out some tune again. The thing is, most of the time she does this, I'll be studying or doing my work, or just about to go to bed ( I sleep way earlier than her).

I mean, I don't mind her singing and commenting bla bla, but I would love it if she keeps it at a minimum noise level. And I know I'm not a perfect roommate either, but I know that I'm not loud and annoy her when she's studying etc.

But how do I tell her this without hurting her feelings, considering that although we are roommates and course mates, we don't hang out together often (she has her own group, I have mine).

Thanks for your help.

PS: She's singing loudly right at this moment. I had to rush through reading my notes for our test tomorrow because I was scared I'd lose my concentration due to my frustration.
How to tell my roommate that her loud singing bothers me?
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