There aren't that many audio encounters of UFOs — that's what makes this sighting above the Columbia River near St. Helens, Oregon in 1981 unique.
We have several minutes of police radio where officers discuss a bright luminous object "like the sun" and better yet — they record a strange sound it is emitting.
J. Allen Hynek reviewed the case and called it a "total puzzle," and analysts concluded the noise does not occur in nature.
Watch video and listen to the sound of a UFO at:
https://www.youtube.com/watch?v=p_jd0hJJO3o