Screaming or howling in Albany County, New York

In mid July, I was sitting at my computer at night, playing a computer game, with the television on behind me. I was watching my sister's dog while they were on vacation, and she was laying down in the other room. At perhaps 7pm or 8pm I heard a howl in the distance, very far behind my house. This is not uncommon, since there is a heavily wooded area where there are hills, and bears often live in the area. A call from a mother to a cub is not unheard of, especially in evening hours. I made sure the dog was in the house and then went to the back and shut the back door. I was not scared of anything getting in, but the dog often will run through a screen door to get to honking geese passing by, a neighbors dog or even a rabbit if it sees one in the back yard. I heard the same, distant howl again a few minutes later and dismissed it. I went back and played my video games for another hour, and then I heard the sound again, but it chilled me more so then I can ever explain in words to another. The noise was not a bear, nor could any bear ever make such a sound Bears make sounds which are deep and even grunting, however this was one that can only be described as a 'screaming howl.' What shook me so much, was that the sound litteraly was just outside my window, perhaps 20 feet or so, and was so loud, I litteraly almost fell out of my seat, it shocked me so baddly. In the summer my windows are open, but to discourage bugs I keep the blinds closed. My window is perhaps 8 feet off the ground on the side of the house, just to give a feel for the area. Immediately my heart raced so fast, it hurt. I knew for a fact, all I had to do was draw the blinds open and I could see what it was, since it was still light out, yet I could not. I was paralyzed for the first and only time in my life. I waited, expecting to hear the sound again, yet did not. Finally after about a minute, I went out of my room and went into a more central room in the house trying to get away fom the sound, yet I would be damned if I would go near one of the screen doors. In my parents room I found my sisters dog, and this animal, who usualy will bark and growl at anything, was laying in a corner, curled up and it had deficated all over the floor. As soon as it saw me it just whimpered. I closed the door and I myself sat down near it and waited for perhaps 10 minutes and after that, finally gathered enough courage to shut and lock all the doors, and didn't hear or see anything afterwards. The dog refused to come out of the room the entire night. I am a 23 year old male who is 6 feet tall and 260 lbs, yet I was terrified plain and simple. I had no idea what it was, and I still do not to this day. I did not tell my parents of relatives, because they will simply say it was a bear, and perhaps it was, but I have NEVER heard a bear, nor any other animal make such a sound before.