Computer Fan Whir

How it's made

Source

one seven-blade axial cooling fan in a desktop computer, already running at 650-2600 rpm. Blade passage creates a 76-303 Hz tone with five progressively weaker harmonics; pink turbulence supplies the continuous air bed, rather than making the whir a bare oscillator.

Airflow

broad noise from 110 Hz to 2.5-6 kHz brightens with speed. A softer white-noise grille layer around 0.9-2.3 kHz is lightly modulated at blade passage, creating diffuse rotating sidebands.

Body

broad, damped housing bands at 185 and 510 Hz colour the air; a weak twice-shaft motor tone and its second harmonic support the blade tone. Enclosure increases body and absorbs high end.

Envelope

continuous steady running, without a startup or shutdown. Speed breathes by less than 0.7 percent over seconds; pitch, airflow level and brightness follow the same smooth control. One- and three-cycle load variations complete whole periods in the requested loop duration.

Variation

seeded phases vary the load cycle and harmonic interference. Rotor imbalance adds shallow once-per-revolution modulation. Presets cover idle, full load, a small fast fan and a muffled closed tower. The source is dry and almost mono; only the turbulent air has modest width.

Cleanup

sine partials avoid aliasing; low-Q filters avoid whistles, a 35 Hz high-pass removes subsonic pressure, and the engine crossfades the stochastic airflow at the loop join.

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