Busy Street at the Kerb

How it's made

Source

a kerb beside a road. Four layers: far traffic (turbulent roar of many tyres), two or three idling engines close by, individual cars driving past, and occasional horn blips.

Bed

tyre/road noise is pink noise band-limited to ~120 Hz–2.5 kHz, decorrelated left/right, breathing slowly (drift ≈ 0.15 Hz) as distant traffic bunches up at lights.

Idle

a 4-cylinder engine at 700–800 rpm fires at ≈ 24–27 Hz; the exhaust pulse train is a low-passed sawtooth (harmonics up to ~300 Hz) with ±3 % rpm wander and a slow misfire-like amplitude lumpiness (≈ 3 Hz).

Passing cars

each pass lasts 4–7 s. Level swells in and out (rise 45 %, fall 55 %), tyre noise is band-passed at 600–1800 Hz and drops ≈ 6 % in centre frequency as the car passes (Doppler), a 90–150 Hz engine drone glides down by the same ratio, and the car moves across the stereo field from one side to the other.

Horns

a two-note horn (≈ 400 and ≈ 480 Hz, a minor third apart, pulse buzz, low-passed at 2.5 kHz) blipped for 0.12–0.4 s with a 15 ms attack, mostly sounding as a short pair.

Variation

`rng` draws pass direction, speed, pitch, level and horn timing for every event; presets move the balance between the layers (rush hour = more passes and roar, side street = sparse passes and idle).

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