Spectral subtraction is a technique used in audio processing to reduce noise from a signal. It works by analyzing the frequency spectrum of a sound, identifying the noise components, and subtracting them from the original signal. This helps to enhance the clarity of the desired audio, making it easier to understand or enjoy. The process involves transforming the audio signal into the frequency domain using methods like the Fast Fourier Transform (FFT). Once the noise is identified, it is subtracted from the overall spectrum, and the modified signal is transformed back into the time domain, resulting in a cleaner audio output.