Noise Sources

Noise has no fundamental, yet it supplies drums, breath and texture.

Related

TimbreEqualizerDrum KitModern

The question

Why does noise sit beside the oscillator on a synth? It has no pitch and seems useful only for hiss, yet drums, breath, wind and film depend on it.

How it works

Noise is a stream of random samples. White noise carries equal energy per hertz, brightest to the ear. Pink noise falls three decibels per octave, closer to rain. Brown noise falls faster and leans low. Send noise through a band-pass and raise resonance; a recognisable pitch appears near the centre frequency, and that is how snares and cymbals form. An envelope decides short hit or long stream of air.

Settings and what you hear

Noise colour sets the balance of bright and dark, level sets presence in the mix, and filter type and cutoff set weight. White noise is television snow, pink is rain, brown is distant traffic. A high-pass thins and brings noise forward; a low-pass muffles and pushes it back. Short decays suit cymbals, long decays suit wind and beds.

What to listen for

Start with the seashore sample and hear spray and low surge at once. Then hear the 8-bit kit, where cymbal hiss contrasts with the pitched kick. Finally sweep a band-pass across noise and notice the sense of pitch appear and vanish as the centre moves.

Common misconceptions

That noise is useless because it has no pitch; that it is only a special effect, when it is in every kit and breath; that more noise means power, when excess smears the midrange.

Sources

• Curtis Roads, The Computer Music Tutorial — noise spectra and filtering checked, not quoted
• Udo Zölzer, DAFX — Digital Audio Effects, noise generation chapter — background checked, not quoted

Used for fact-checking only; all prose is original.