While harmonic distortion adds frequencies that are multiples of the original note (which can even sound pleasant, as in a guitar amplifier), inharmonic distortion creates dissonant and "wrong" sound artifacts, as its frequencies have no mathematical relationship with the original sound.

It is usually the result of some kind of unwanted modulation process.

The most common examples are:

1. Aliasing (in digital systems): Occurs when a digital converter receives a signal with frequencies that are too high for its sampling rate or when its filters are deficient. This creates inharmonic "phantom frequencies" that muddy the audio.

2. Scrape Flutter (on tape recorders): It is a form of high-frequency vibration that occurs when the magnetic tape scrapes against the machine's guides. This vibration modulates the recorded audio, adding inharmonic components and a harsh sound.