Strange globe sighting--1969.

Thank you for allowing me to share my own story.
Back in July 1969, I was a teenager of 16 yrs old.
I was lying in bed semi-asleep, when a high-pitched sound started.
This sound was like a pure sinewave tone, I would estimate around 10Khz to 15Khz.
I thought it was the cheap table fan on the small table by the window - it was a hot night.
So I went to shut it off, thinking the motor maybe needed oiling, and I'd do that the next day.
My parents and sisters were alseep in their rooms, and I didn't want to wake them by going down the squeaky stairs to the basement for oil.
When I shut the fan off, the noise continued, and seemed to come from outside.
I walked over to the window, which was open, and looked out.
What I saw was utterly amazing to me! Hovering motionless over Mr Allen's roof which was about 150 feet away, was this globe-like thing.
It was about 5 or 6 feet in diameter, perfectly round, and was a dark greyish semi-shiney color.
It just hovered there, not moving, and I kept hearing that "whistle/tone" that I mentioned before.
There were no lights on it.
I went to my parents bedroom and woke my mom up, but she complained that I was goning to wake my dad up - I told her to come to my room, she refused and told me to go back to bed and shut up.
So I went back to my bedroom, and sat by the window, watching that thing, amazed by it.
After about 20 minutes, it literally flew straight up in the air and disappeared, and instantly that sound stopped, like turning off a switch.
The speed of this thing was almost instant, like 500 miles an hour I would guess.
It just vanished! I weant back to bed, lay there and eventaully drifted off to sleep.
But I'll never forget what I saw, and I know it wasn't a dream, because the next day mom confronted me about waking her up the night before.
I've talked about this to others, and the usual response was typical - thay I was making this story up.
But I know better.
I'm not dumb.
Thanks again for allowing me to share this.