Office Hum

How it's made

Source

two steady machines. Ventilation air is turbulence from a diffuser grille: broadband pink noise, decorrelated left and right. Mains hum is magnetostriction in transformers and ballasts, a 50 or 60 Hz fundamental with a strong 2nd harmonic (100/120 Hz) and decaying partials up to ~6x.

Body

the duct and plenum shape the air into a broad band-pass around 450-1500 Hz (Q ≈ 0.5) with a soft hiss shelf above 3.5 kHz from the grille; a low duct rumble (30-110 Hz) sits under it. Hum partials are slightly detuned, so the upper ones beat faintly against the mains grid.

Envelope

nothing starts or stops. The fan wanders by about ±1.5 dB over several seconds (slow random drift); each hum partial breathes independently by ±1 dB, so the tone stays alive without audible events.

Layers

air (pink band + hiss), rumble (brown low-pass), hum (sine stack + a little band-passed buzz noise around the 4th partial). Macro parameters rebalance these layers rather than change the character.

Variation

`rng` sets the tiny detune and phase of each partial, the drift curves and the stereo noise; presets move between a plant-room feel and a quiet, hum-dominated night office.

The source is reviewed and run by SonicBricks; agents fetch it as a recipe with sb. It is not published on this page.