Deep Moaning In The Stairwell

About 2 or 3 weeks ago I was leaving my grandmother's house. She lives in an apartment complex designated for veterans and their wives, as well as people with fixed income, ie pensions. My boyfriend was waiting for me outside so, rather than taking the elevator which might I add was very slow, I took a stairwell that I always use to come and go. Not once has this stairwell door ever made any other sounds other than clicking shut.

Well...I opened the door and was about to make my way down the stairs, when the door made the most awful sound of some kind of demonic moan as it closed. I stood in front of it, frozen in shock rather than fright until it stopped. It was a chilling sound and I didn't feel scared or anything, but I was uncomfortable enough to run out of there fast. The sound and scenario reminded me of that one stairwell scene from The Grudge (Ringu). Since it happened and like I said, before as well... The door has never made that kind of noise.

That's not the only incident that has occurred in my grandmother's apartment. I was sleeping over about a month ago (my cousin lives with my grandmother). My cousin had the bed and I had the floor. I couldn't sleep because I was paranoid a spider would come out from under the bed and crawl on me. I started to get itchy thinking about it, so I got up and used the bathroom. When I came back, I brushed my sleeping area off and lay down. As soon as I got a comfortable position, I heard a whispered voice that sounded as clear as day like my mother say, "Hello" right next to my ear. I lay there for a couple of seconds not knowing what to do, should I answer?... Should I not?...

Then I remember from stories and articles I've read that ghosts or evil spirits can disguise themselves or their voices as the people you love, so when you respond it invites them to harm you. I didn't answer, but instead lay there silent until I fell asleep. I asked my cousin the next morning if she had maybe been awake and said something to me but she told me no, and besides it didn't even sound like her. It sounded like my mother.

Later that night something else pretty bizarre occurred, but I'll leave that until my next story. Thank you for reading, input would be appreciated.