Most common-or-garden ceramic capacitors are barium-titanate formulations, which is a perfectly decent piezo electric material
and ferro-electric - ferro electrics are automatically microphonic and have high dielectric constants -
hence their use in high value ceramic capacitors and piezo elements.
Such capacitors are used where the precise value and linearity is not important - ie decoupling. Not a
good choice for an audio amplifier though.
Lower value ceramics can be non-ferro-electric and much more temperature-stable - there are many ceramic dielectric materials to
choose from