Footstep on a Hollow Plank Bridge

How it's made

Source

one step on a suspended plank bridge. The heel lands first, the sole rolls onto the toe 70–120 ms later; each contact is a 2–8 ms low-passed noise burst plus a soft low thump from the body weight.

Body

the plank rings in damped wood modes (size 1.6–2.4 puts the first mode near 150–250 Hz); the open space under the deck adds a hollow cavity resonance at 90–160 Hz (Q 5–12) that gives the knock its boom.

Creak

the rope and plank joints stick-slip under load. Rough saw-like pulses at 40–80 Hz excite two narrow resonances (≈ 420 Hz and 900 Hz) that glide down 10–20 % over 0.3 s while the load settles.

Rattle

the bridge sways at 2–3 Hz after the step; loose hardware and neighbouring planks click as sparse, band-passed impulses (1.5–4 kHz) gated by the sway lobes and decaying over about 0.5 s.

Envelope

heel and toe are over in 0.25 s, the creak peaks around 0.25 s, the rattle fades by 0.7 s.

Variation

`rng` jitters the heel-toe gap, plank tuning, creak pitch and rattle clicks; macros set weight, plank hardness, bridge hollowness, creak and sway amount.

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