[ksaj]

I noticed David Lee Roth (Van Halen and solo) does exactly that polyphonic vocal riff in a number of songs.

[tyingq]

His vocal track separated. Try around 3:25 or so: https://youtu.be/IArxakPsPE0

[ksaj]

It's only 3:28 long. I think you meant 2:25 since he does a really good overtone at about 2:30. Thanks for this perfect example. Usually I'm the only one who knows wtf I'm talking about when I mention such obscure things.

[tyingq]

Oops, yes...2:25.