Train Carriage Interior

How it's made

Source

steel wheels running over rail joints. Each wheel hitting the gap is a 1–3 ms broadband tick plus a 20–60 ms low thud (80–200 Hz) that the carriage floor and frame carry into the cabin. Between joints, wheel and rail roughness and the air flow make continuous low noise.

Rhythm

a bogie has two axles ≈ 2.5 m apart and a carriage two bogies ≈ 17 m apart, so every rail joint (≈ 25 m apart) gives a clack-clack pair, a gap, then a second pair. The joint rate sets the train speed; the period is snapped to a whole number of joints so the 12 s loop holds complete patterns.

Body

the floor and wall panels ring in a few damped modes (≈ 150, 310, 540 Hz, 60–140 ms) under each clack. Loose panels and fittings answer with a short, dry rattle burst (0.6–2.5 kHz, 0.1–0.25 s) after every clack, plus a faint sparse rattle between them.

Envelope

the rumble is a steady brown-noise floor under 140 Hz and a 90–900 Hz roar, swaying ±12 % at 0.3–0.5 Hz as the body rocks on its springs; nothing else changes over the loop.

Variation

`rng` jitters joint timing (±4 ms), clack strength, tone, and every rattle burst. The parameters set speed, rumble weight, clack hardness, rattle amount and cabin muffling.

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