Report 187: Unusual vocalization heard near Sandy

Before I go any further, I'd like to emphasize that I am not sure that I actually heard a bigfoot sound.  I am mainly putting it on here because I have thought about it in depth (that's why the delay in reporting), and the only thing in my memory that has any resemblance at all to what I've heard is the past audio recordings of bigfoot (although what I heard had better audio!).  I still wonder if this was a bigfoot, how or why it would have been near a town, but I have no other explanations. I was in Sandy, Oregon with my family during the weekend of July 21-23, 2000. We were staying at the Sandy Inn, which is just west of the main part of town.  It was hard to sleep the night of the 21st; it was very humid and some thunderstorms did move through about midnight or so.  I was up several times during the night; either to shut the window, open the window, turn on the air conditioning, etc.  I got up once around 3 or so in the morning on the 22nd after the storms passed. I was sticking my head out of our 2nd story window, enjoying some cool air and kind of looking off into the woods toward the north.  There was not a sound anywhere (that I could hear). No cars on the highway, nothing.  Then I heard a very indescribable sound. I thought at first it was tires screeching but as the seconds passed I realized a car would have to be burning rubber for a long ways. Then as I kinda cleared my head, I thought it sounded like a man screaming, or better yet, wailing.  But I've n ever heard a human do a sound like that either. It was not a moan or howling with an "o" sound, it was more like "eye-eeee--ah-eye-eee". Very high pitched. It won't do me much good to try to interpret the sound in letters.  But the way the pitch of the sound went up and down so fast, I've never heard any animal or human do that, and I've heard quite a lot of animals.  If a a human did what I heard, they'd bust their vocal chords. It went on for about 20 seconds-maybe a little longer, but not sure of that. It did seem to kind of trail off at one point then come back. I know it was long enough for me to get a good listen.  It was not close by, either. The window faced toward the north, so it's possible that's where it came from but I can't be sure of that. It seemed like it was off in the distance somewhere. When it started, it was rather quiet, and ended trailing off in the same manner it started.  Even though I was a bit groggy, it was wierd enough to wake me up and even scare me a bit.  I didn't think too much of it at the time but the next morning I was thinking to myself, "What was that?"  I didn't report it or consider that until now because I wasn't sure and after a while I honestly had forgotten about it until something in my mind triggered it again.  All I can say is, if it wasn't a bigfoot, fine.  But please tell me what it was