Factory Steam Whistle

How it's made

Source

a steam jet excites three whistle bells; filtered white noise models the 0.8–7 kHz air jet.

Body

three locked edge tones at 1:1.25:1.5, with weaker second and third harmonics and breath resonances. Alternative open-fifth and close-cluster bell sets retain the multi-chamber factory signal character.

Envelope

steam opens in 45 ms; bells speak over 110–170 ms with staggered thresholds, hold to 2.25 s, then lose pressure over 0.4 s. Residual steam fades by 2.95 s; the complete signal ends at 3.05 s.

Modulation

pressure raises pitch from 95% to full tuning and sags to 97% at closure; independent slow wander and 4–6 Hz flutter impart small pitch and amplitude fluctuations without a siren sweep.

Layers

additive pipe harmonics dominate, low-Q jet noise surrounds them, and narrow breath bands couple turbulence to each bell. The source is dry and centred, without baked-in factory reverberation.

Variation

named random streams vary tuning by 0.15%, onset by 12 ms, and turbulent pressure per bell. Presets alter bell size, chord spacing, steam balance, harmonic strength and worn-bell detuning.

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