Reply #53: There's the line-frequency series input inductor;

[Tesha]

that's the one that buzzes at 120 Hz (twice the
line frequency) and can be heard by us. That
input circuitry is essentially identical for CFLs
and LEDs.

Then there's the magnetic components associated
with the voltage conversion. These are different between
CFLs and LEDs but in both cases, they operate at
high (ultrasonic) frequencies and the noise they usually
produce can't be heard by us.

Tesha