Metal Scrape on Concrete

How it's made

Source

a steel edge dragged over concrete; pink/white friction spans 180 Hz–7 kHz, with fine grains.

Body

contact excites damped metal modes near 370, 863, 1595 and 2530 Hz, scaled by object size; 65–180 ms decays represent the strong damping of an object held against a hard rough floor.

Envelope

18 ms contact onset, uneven pressure through a 1.75 s drag, 120 ms slowing release, then a brief metal settling tail. All layers are dry and the output fades to zero by 2.05 s.

Modulation

shared 6–18 Hz wandering stick-slip pressure modulates grit and screech; sliding speed bends the 620–1800 Hz friction fundamental and its 2nd, 3rd and 5th harmonics without a riser sweep.

Events

irregular 10–38 Hz asperity catches make 2–5 ms noise kicks with 15–45 ms gritty releases; they excite the metal body and remain distinct from the finer 900–2700 grain contacts per second.

Variation

seeded pressure, frequency drift, grain timing and catch strength; mass lowers modes, grit raises abrasion, screech raises tonal friction, chatter deepens pressure interruptions.

Presets

heavy drag is low and grinding; thin edge is bright and squealing; rough slab skips and chatters; short scuff is a compact, mostly granular stroke. Length scales the entire gesture.

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