Here's some commentary I previously wrote on BaTiO3 capacitors:
Problems of BaTiO3 Capacitors
Even today, ceramic capacitors are most commonly made from Barium Titanate (BaTiO3( sandwiched between two electrodes. MLCCs (usually for power supplies) use the same technology in stacks to deliver high capacitance in small volume. This is great for miniaturization, such as in cell phones. (Tantalum is also very dense, but it is expensive and a conflict mineral, and the capacitors are, to used to be at any rate, more prone to failure.) Aside from a wonderfully high dielectric constant, BaTiO3 is a horrible material because it also is piezoelectric and microphonic.
But the joy of BaTiO3 doesn't stop there.
BaTiO3 is pyroelectric (temperature changes result in a voltage potential across the electrodes) so it can be used as a heat sensor. Then there is the DC bias problemwhich reduces the capacitance with applied DC voltage, so there is the additional property of being non-linear. (This can be used to create a voltage-dependent capacitor.) Plus it has a time-dependent dielectric breakdown from applying a constant DC bias voltage, which is in addition to the reduction in capacitance.
So BaTiO3 capacitors would not be considered audiophile grade, even with a liberal interpretation for "audiophile grade", when used in the signal path. The main use for such capacitors is decoupling in high-speed digital circuits where the horrid properties do not matter and the item is usually disposable after a few years.
BaTiO3 capacitors are also suspected of inviting roaches and rodents into the home, although, to be fair, this has been disputed. Nobody talks about BaTiO3's misbehavior in polite company. I replace them with 1% poly film capacitors and thus have no roaches or rodents in my home.
