Clipping (or "clipping") is a form of distortion that occurs when an audio signal is too strong for the system processing it, causing the peaks of the sound wave to be "cut off" or "flattened".

When the amplitude of a sound wave exceeds the maximum level that the circuit or digital system can handle, the peaks of the wave are clipped.

This transforms the original waveform, which was rounded (like a sine wave), into something more like a square wave.

Analog vs. Clipping

Digital

Although the result is always distortion, the sound and consequences are quite different.

Analog Clipping

Occurs when the voltage of the audio signal exceeds the voltage of the circuit's power supply. The result is the addition of harmonic distortion, which are frequencies musically related to the original sound. In small amounts, it can even sound pleasant and "warm," like in the overdrive of a guitar amplifier.

Digital Clipping

Occurs when the signal exceeds the maximum point of the digital scale (0 dBFS - decibels Full Scale). Since there are no numbers above 0 in the digital world, the system simply clips the peaks. This abrupt clipping generates a large number of high-frequency harmonics which, in turn, cause aliasing. The result is an inharmonic distortion, with dissonant and non-musical artifacts, which is much harsher and more unpleasant than analog clipping.