Controlled distortion adds harmonics that make quiet or masked sounds more audible without changing their frequency

Distortion adds new harmonics related to the original signal frequencies. In a mix context, this makes sounds audible in frequency ranges where they previously had no content — for example, a bass guitar with energy only at 40-80Hz becomes audible on small speakers after adding harmonics at 80-200Hz. Rich Costey: ‘Distorting lead vocals is so commonplace nowadays that to me it’s the same as distorting a guitar or a bass.’ The Aphex Aural Exciter process uses this principle: aggressively high-pass the signal, compress it, then drive it into distortion to generate controlled high-frequency harmonic density, which adds ‘air’ and presence. Parallel distortion (via send effect) is usually preferable to insert distortion, giving independent control over how much the added harmonics are blended in.

Examples

A sub-bass synth part has fundamental energy at 30-50Hz but disappears on laptop speakers. Running it through a soft-clipper in parallel adds 60-100Hz harmonics, making it audible without changing the felt sub energy on large systems.

Assessment

Explain why distortion can make a bass instrument audible on a small speaker that cannot reproduce its fundamental frequency. Why is parallel distortion processing generally preferable to inserting a distortion effect directly on a track?