The process of isolating one stage of an amplifier from another. Decoupling prevents unwanted oscillations (see WFTD Oscillator) and other noises that may occur due to unwanted feedback through common power supply connections (see WFTD Coupling). It also provides further filtering of the power supply to reduce any lingering AC ripple, producing a cleaner DC supply for the low-level preamp stages. This decoupling is often accomplished by adding a resistor in series with the power supply to a gain stage and a large-value electrolytic capacitor from the supply to ground after the resistor, however, there are a number of other designs employed as well.
In acoustics decoupling refers to mechanically isolating masses from one another, particularly masses that are vibrating, such as speaker cabinets. This prevents the undesired transmission sound through additional materials that can result in a compromise in sound quality to he listener or at the microphone.