Bobert, I used to hypnotize hundreds of people for a video tape anthology project for these kind of experiences.

Of all my unusual sighting experiences the most bizarre I had took place in Wheaton MD. As the triangular craft passed within 100 feet of the roofline of our garden apartment, my wife and I sensed danger and we both came off the 3rd floor porch and sat down while a deep electrical throbbing humm penetrated everything in the room.
We remained silent and continued to listen to what seemed like an immense dynamo. No crackling sparks or shocks but we definetly felt electrified. The sound is still clear in my mind and reproducible.
There were few if any high frequencies.

Get this, we didn't discuss it after it passed.
In retrospect that seems so wierd to me now that I can not explain our behavior.

USually people say the events they witnessed were without sound.
Not true for us that time.