I started my new job a week and a half ago. The coworker who sits next to me wears big, over-the-ear headphones to listen to music most of the day - no big deal. But she frequently starts singing along to whatever she is listening to in a fairly high-pitched tone. And I don't think she realizes how loud she can get when she does this. I have resorted to taking out my hearing aid and to wearing my own headphones as a result, and sometimes, I can hear her over my earbuds.

As the new guy, I'm not sure how to address this.