Ceramic Capacity Noise

However when a capacitor is mounted on a board the vibration increases and when the cycle of the amplitude reaches the audible frequency range 20hz 20khz of humans it can be heard as a noise.

Ceramic capacity noise.

For example the noise sounds like a hum hiss or a high pitched tone. An acoustic sound may be heard emanating from the capacitor itself. Protecting the power source from electrical noise generated within the circuit and protecting the circuit from electrical noise generated by other devices connected to the same power source. When capacitors are used for power supply decoupling they serve two roles.

There is almost no noise generated by the capacitor itself. Johnson nyquist noise thermal noise johnson noise or nyquist noise is the electronic noise generated by the thermal agitation of the charge carriers usually the electrons inside an electrical conductor at equilibrium which happens regardless of any applied voltage thermal noise is present in all electrical circuits and in sensitive electronic equipment such as radio receivers can. In some cases the piezoelectric effect may result in the appearance of electrical noise while in other cases.