How can I make her shut the heck up?

My grandmother keeps making these "uh huh huh" noises that's kind of like a moan, but it's not (it reminds me of Butthead from Beavis & Butthead), but it's a deeper sound. Anyway, it's driving me up the wall. She denies having a problem, but I don't fully believe her. She says it's comforting to make the sounds. However, it's not comforting to me, it's making me crazy - literally. It would be one thing if I just heard it when we're in the same room together, but I hear it all over the house - upstairs too. I can't get away from it. If I put headphones on or turn on something to drown out the sound, I wouldn't be able to hear her if she called or paged me. I've told her of this but she keeps making these sounds. Oddly, when I sneak up beside her when she's making these sounds and then she suddenly realizes I'm there, she starts reading the clues/questions in her crossword puzzle as to cover up the fact that she had been making those sounds. The other night she was making the sounds for two hours straight. I was upstairs trying to work on a complicated computer-email problem. All of a sudden I snapped and found myself yelling "shut up" and didn't realize I was yelling until I was actually doing it. I didn't intend to yell, it just came out. Nothing like that's ever happened to me before. Any suggestions on what to do? If this crap continues, I may have to take drastic measures. I may have tell Grandma to knock it off or I'll play some lovely hip-hop music for her everytime she does it. Considering she's intentionally making the sounds despite that I've told her I can hear her all over the house and it's annoying, then I don't think there's anything wrong with giving her a dose of her own medicine. It's not like she has dementia and can't help it. She knows what she's doing. And like I said, I can hear her all over the house - I can't get away from it.