When I am touching myself, I can't help making certain sounds; a couple times my mom has barged into my room asking if I was in pain (thank god she isn't too bright; she never figured out what I was actually doing). It kind of bothers me; does any one know any tricks that I could use to keep myself inaudible?

This is also a little off topic, but it explains the necessity of an answer to the above question; I'm horny all the time. I have to masturbate three or even four times a day or I feel like I'm going to go insane. I don't know if this is normal for a woman my age (eighteen) or not.