Siren Sweep

How it's made

Source

an electronic emergency horn driven continuously through a smooth rising/falling pitch cycle. The fundamental sweeps 520–1120 Hz by default; five phase-locked partials model the diaphragm drive.

Body

harmonics 1, 2, 3, 4 and 5 have decreasing gains; upper harmonics strengthen near the sweep crest. A broad 1550 Hz horn band and a 2.5–5.7 kHz low-pass colour the driver without narrow resonances.

Layers

filtered air noise sits roughly 40 dB below the tonal source; no sub drone or baked reverb.

Envelope

continuous sustain, with 16 percent smooth level breathing as pitch rises; zero slope at the pitch turnarounds. A 6 s loop contains an integer number of complete wails, with no retrigger.

Modulation

a sinusoidal control drives phase-continuous oscillators at exact harmonic ratios. The carrier completes whole cycles at 6 s for integer-Hz settings, keeping the tonal seam continuous.

Variation

controls set low pitch, sweep span, cycles per 6 s and horn brightness; seeded noise varies only the quiet air layer. Presets cover slow low wail, rapid urgent sweep, high alert and muted horn.

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