[CAUT] False beats

[James Ellis]

I'm reading the comments about false beats, and I want to add just one
more, which does not disagree with anything said so far.  Anything, and I
mean ANYTHING, that causes the string's vibration to wander out-of-plane
and take on an orthoghnal mode where it's frequency in one plane is not
quite the same as in another plane, will cause a false beat.

Jim Ellis