The self-noise is the current noise generated by the system itself. As long as the temperature exceeds absolute zero, all electronic components will produce their own noise. The movement of electrons produces noise. The component noise and the noise of the circuit where it is located are part of the audio track. Adding the two noises results in the device's own noise. Similarly, by combining all these devices in an audio system, the system's own noise can be obtained. This self-noise represents the inherent noise of the device or the system. The difference between this noise level and the signal level in the device is the signal-to-noise ratio.