Ok I saw this on a video. On one of the Apollo flights there was a mysterious sound that was never explained. They played a clip of the sound and it sounded like a creepy screaming sound. On the clip astronauts were also commenting on it and trying to determine what it was. Oh BTW... the video was about UFOs and aliens.

 

Is there any truth to this, and if so is it true that no explanation for the mystifying noise.

 

I can't find any info on it.

the noise would have to come from inside the craft or be caused by an impact. no possibility that it was aliens unless they entered the craft or suffused the space around the craft with an atmosphere.

If I remember correctly the astronauts often heard extraneous noises coming from outside the cockpit, but you have to bear in mind that the phrase "outside the cockpit" includes most of the spacecraft, much of which is (more or less) open to the vacuum of space. I'm sure the explosion of the Service Module in the Apollo 13 mission, for example, made a hell of a bang. Since the ship is physically connected, there's plenty of metal for the sound waves to propagate along.