"Phil Allison" wrote

However, real world discontinuities have limited bandwidth and
hence a non
infinite series expansion - so they CAN be exactly
represented by a
series of sine waves.

Only if they are periodic.

Nothing in the real world is periodic. Specifically, nothing in
music is precisely periodic. If you look you will see that it is the
assumption of periodicity that most concerned me.

Your daft notion of instantaneous frequency won't impress, so don't
bother embarrassing yourself again. Unless of course you know how to
detect frequency with one instantaneous sample.

cheers, Ian