Text-to-SFX: procedural sound effects

1. First attempt (2026-02)

An AI coding agent (opencode with GLM-4.7) wrote one Python generator per sound, using sine waves, noise, filters and envelopes. Simple sounds came out well; the door sounds did not.

Thud 0.5 s. Click, a pitch-dropping body and a mid-range knock. Revised 2026-10: the original was almost all below 100 Hz and silent on laptop speakers.
Button click 50 ms. High-frequency (2–4 kHz) blip with an instant decay.
Explosion Low rumble (20–50 Hz) plus broadband noise and a long decay.
Flying saucer Rise-and-fall sweep with a metallic texture, passing by with Doppler shift.
Gravel footsteps Stone impacts per step, irregular timing, panned left to right (use headphones).
Siren (basic) Two alternating tones, 500/800 Hz.
Siren (US wail + Doppler) Wail sweep moving past the listener.
Siren (EU hi-lo + Doppler) European two-tone moving past.
"Door creak" The first door creak attempt. It sounds like wind, and was later renamed "wind whistling".
Hinge creak The first stick-slip hinge attempt: noise bursts plus a separate tone. Not convincing.

2. Second attempt: the squeaky hinge (2026-10)

With Claude Code (Claude Opus 5.5), we researched friction acoustics, built a physical model, then measured 23 real squeaks. Real squeaks turned out to be sequences of parts: steady pitches with sudden jumps, glides, and clean stretches that break into clicks, all driven by sharp stick-slip pulses. Each sound below is generated by our code from those measurements.

stepped squeak — steady pitches with sudden jumps between them

#1	1.6 s	analysis
#2	1.1 s	analysis
#5	1.6 s	analysis
#11	1.2 s	analysis
#22	1.5 s	analysis

gliding squeak — one continuous pitch slide

#4	2.2 s		analysis
#21	1.3 s		analysis

squeak → creak — a clean squeak that breaks into separate clicks

#0	4.6 s	analysis
#3	0.8 s	analysis
#6	1.6 s	analysis
#8	1.1 s	analysis
#13	1.1 s	analysis
#14	0.6 s	analysis
#16	1.6 s	analysis
#18	2.7 s	analysis
#20	1.3 s	analysis

creak / ratchet — mostly individual clicks

#7	1.9 s	analysis
#9	2.2 s	analysis
#12	2.6 s	analysis
#15	0.7 s	analysis
#17	1.4 s	analysis
#19	0.9 s	analysis

low groan — low and wobbly

#10

0.6 s

analysis

3. Details

Reference recording: Squeaky Door Hinge Opening Sound Effects (SoundEffectsFactory, YouTube). It is not redistributed here (unclear provenance); the analysis page links each squeak to its timestamp in the video.
Full analysis of the 23 squeaks: spectrograms with measured pitch, five categories, a feature table, and how each rebuild compares with the original.
The physics model (Hinge Lab): a Rust app with sliders that simulates stick-slip friction. Physically right (it squeaks only within a speed window, and oil silences it) but it sounded too smooth, which is what led to measuring real squeaks.
Research briefing: the physics of squeaks and creaks, with equations and primary sources (Akay 2002; Avanzini, Serafin & Rocchesso 2002; Farnell 2010).
Status and next steps: what remains for each part.

All audio on this site is generated by this project's code (MIT).