What is a microphonic?

In electronics, "microphonics" (or microphony) refers to the phenomenon where mechanical vibrations are transformed into unwanted electrical noise or frequency shifts. In oscillators, mechanical tapping or shaking changes the physical dimensions of components like coils or variable capacitors. This subtly changes their electrical values, thus altering the resonant frequency. While the prefix "micro-" might suggest a connection to a voice microphone or audio amplification, this is a distractor. The term is used because the electronic components are unintentionally acting like a microphone by picking up sound or vibration. To prevent microphonics, components in critical oscillator circuits are often potted in wax or epoxy, or mechanically secured to prevent them from vibrating.