Air Brake Release

How it's made

Source

compressed air escaping a brake relay valve; independent white-noise jets open in 3 ms. A second outlet, delayed 18-105 ms, models unequal brake-line lengths rather than an echo.

Body

broad nozzle emphasis falls from 1.8-4.5 kHz to 0.7-1.6 kHz as pressure drops; the low-pass falls from 3-10 kHz to 1.2-3.3 kHz. Low-Q filters avoid a pitched whistle.

Layers

pink-noise chamber turbulence at 100-850 Hz gives the opening a short pressure puff. A 7 ms noise excitation drives valve modes at 390, 1170 and 2380 Hz, damped in 14-38 ms.

Envelope

3 ms attack, strong initial burst, 72% amplitude lost by 0.35 of the release; the final 30% is a quiet, dark residual hiss. Default air flow ends at 1.42 s, then silence.

Modulation

low-passed noise varies jet amplitude by up to 8%; pressure drives level and colour.

Variation

seeded nozzle tuning varies by 3% and opening timing by 0.5 ms. Presets change release time, muffler brightness, chamber weight and the delay/strength of the second outlet.

Space

dry, mono point source for placement on a vehicle; no room or artificial stereo motion.

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