Knocks Behind the Wall

How it's made

Source

three deliberate knuckle blows at 0, 0.9 and 1.8 s, with identical spacing and no extra hits. A 3 ms attack and 16 ms soft noise contact excite the concealed wooden surface.

Body

damped inharmonic panel modes at about 145, 329, 548 and 851 Hz, T60 90–280 ms; a 72–112 Hz joist mode and 130–202 Hz cavity carry the low thud through the partition.

Occlusion

two low-pass stages at 430–1750 Hz suppress direct contact brightness; the contact cutoff falls during its first 35 ms, leaving structure-borne low frequencies after the attack.

Envelope

each body falls away within 350 ms, with a dark room decay continuing for 0.7–1.0 s. The final room tail fades by 2.95 s, followed by silence; every strike has a rounded onset.

Space

low-level reflections at 31, 53 and 79 ms feed a small room; the room is part of the cue.

Variation

seeded strength varies by 6% and tuning by 1.5%, without timing jitter or pitch sweeps. Presets model a plaster wall, low floor joists, a thin hollow partition and a distant cellar wall.

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