This reminds me of my grandmother's vacuum cleaner. It had a light on the front and the motor made a sinister (to me) hum as it moved along. As a child visiting her place infrequently, I was actually scared of it. It gave me the creeps.

Another sound which gives me the creeps is the drone of any kind of airship. Don't know why. I wasn't alive through any wars or anything of that kind.

Jenny