One of the facets of the Outer Limits which made the series leave an indelible impression on me is its use of Sound effects. One of those which stand out for me is the Sound effect from the episode "O.B.I.T." (acronym for Outer Band Individuated Teletracer). It's when the human-monitor turns on that surveillance-machine and is surprised to see that the machine is probing beyond its normal range. At that point, the Alien-monster comes into view on the screen. Throughout this brief sequence runs a very Unearthly sound which I can only describe as an electronic whine. The whine also "bends" at intervals as though it's warped, which adds to the already-eerie sound. Maybe Lunk could insert that actual sound into this thread, if it's possible.
That was one of the unique sounds -- there are many others. What eerie sounds do you remember, Lunk?
While I'm at it, now that I mentioned the O.b.i.t. episode, I should discuss the episode itself. Lunk once said that he does Not have the Book which covers behind-the-scenes, but I have that book, so will garner some tidbits from it to post here. In this case, it has to do with the Alien's single cyclopean eye which is situated in the center of his forehead. You would think that the make-up uses a fake eyeball, but the data explains that the ACTOR had to turn his face somewhat SIDEWAYS in order to make HIS own eye appear in the center of the prosthetic make-up. That's why the cyclops eye looks so realistic -- it's because it's a REAL eye!
That eyeball also reminds me of an episode from THE TWILIGHT ZONE where that time instead of a Single eye, the Alien had Three. At first, the special effects artists had experimented with using a "superimposed" image of an actual eye. But evidently that did Not satisfy Rod Serling, so they ended up using the Fake eyeball, which really looks fake to me! Serling could Not have used the OUTER LIMITS method because the Serling version had THREE eyeballs instead of cyclopean, so the "head-turning" would Not have worked in that case.