We look at the processes that can add harmonic content to a sound, for subtle warmth or radical transformation.

You might see a sound engineer as an audio chef, blending the finest ingredients to create the perfect sonic dish. But there’s another food analogy that I think is interesting to consider, that of fermentation. Fermentation is the use of organisms such as yeast and bacteria to transform otherwise innocuous foods into more complex and interesting ones such as bread, beer and chocolate. Similarly, certain audio processes can introduce new frequencies and harmonics that weren’t there before, and which can create spicy new audio flavours and tasty sonic experiences.

Techniques such as distortion, saturation, clipping, resonant feedback and waveshaping are all methods of introducing brand‑new harmonics into a sound. This article will look at a few of the ways to ‘ferment’ your audio in this way, introduce new harmonics and to creatively transform its character.