That is for sure. I wrote software for a small microcontroller based medical treatment device. This unit had some high voltage ceramic capacitors that were 2512 surface mounted types. These capacitors were used in a circuit that was pulsed at 100 Hz. Believe it or not the ceramic capacitors acted like a sound transducer and made the equipment buzz!!! I believe that the hardware engineers eventually "fixed" the problem by putting RTV silicone material along the edges of the capacitors and down to the PC board.

Michael Karas