Capacitor Dielectric Question

[FourT6and2]

I personally prefer how micas sound compared to ceramic, which some say add a gritty texture to the sound. And ceramic disk caps have a tendency to—not be microphonic as some say—but to have piezoelectric properties. You can actually yell into a ceramic cap and hear it through your speaker lol.

That's just another kind of microphonic.

Yeah I guess that's true.

[pdf64]

Note that there are several types of ceramic material used for caps, they're not all created equal.
I think it's the material used for higher value ceramics that tend to have a high temperature coefficient and microphonics; but some opine that they can contribute beneficially to the tone of a guitar amp.