Vocal effect

Since a lot of you have a fairly wide variety of musical taste, I figured maybe some of you could help me with this. George Harrison uses a vocal effect on the Beatles song "Blue Jay Way" and I'm wondering if anyone knows what it is called and/or how it works. As another example, Jerry Cantrell uses the same effect on his song "Breaks My Back".

I think it might be a phaser of some sort. You get a phasing effect by playing the same thing on two tape machines slightly out of sync or something like that.

Yep, it's tape phasing, or "flanging" as it is more commonly known. I think it was actually George Martin who invented that term as a joke with John Lennon, and it has since become official recording parlance.

I got it right! Amazing....

That's all it is? A phasing effect? I wonder why it sounds so different from the "doubling" effect John Lennon was always using which was essentially done the same way.

Automatic Double Tracking or "ADT" is essentially the same technique, it uses two tape machines out of sync with each other, but the delay between them is a few milliseconds greater than flanging so it sounds like there are two voices rather than one creepy voice.