Sound is off by default. It starts only when a visitor clicks "Enter with sound" or the ♫ Sound button (browsers block autoplay).
Approach modeled on the John Xuna slideshow (https://xuna.com/slideshow): a music bed per chapter mood, a short narration per chapter that ducks the music, light sound effects.
| File | Used for | Title | Artist | Licence | Source |
|---|---|---|---|---|---|
music/carefree.mp3 | Overview + most chapters | Carefree | Kevin MacLeod (incompetech.com) | CC BY 4.0 | https://incompetech.com/music/royalty-free/mp3-royaltyfree/Carefree.mp3 |
music/fluffing-a-duck.mp3 | Funny commercials (~1988) and Comedy & media | Fluffing a Duck | Kevin MacLeod (incompetech.com) | CC BY 4.0 | https://incompetech.com/music/royalty-free/mp3-royaltyfree/Fluffing%20a%20Duck.mp3 |
music/inspired.mp3 | Army, private chapters, Now, The lesson | Inspired | Kevin MacLeod (incompetech.com) | CC BY 4.0 | https://incompetech.com/music/royalty-free/mp3-royaltyfree/Inspired.mp3 |
Attribution: "Carefree", "Fluffing a Duck" and "Inspired" by Kevin MacLeod (incompetech.com). Licensed under Creative Commons: By Attribution 4.0 License — http://creativecommons.org/licenses/by/4.0/
Changes: trimmed (Carefree first 80 s, Inspired first 85 s, Fluffing a Duck full length), fade in/out added, loudness-normalised (−20 LUFS) and re-encoded as 80 kbps MP3 with ffmpeg. No other changes.
| File | Used for | Original | Pack | Licence | Source |
|---|---|---|---|---|---|
sfx/open.mp3 | Chapter opens (zoom in) | maximize_006.ogg | Interface Sounds 1.0 by Kenney | CC0 1.0 | https://kenney.nl/assets/interface-sounds |
sfx/close.mp3 | Chapter closes (zoom out) | minimize_006.ogg | Interface Sounds 1.0 by Kenney | CC0 1.0 | https://kenney.nl/assets/interface-sounds |
sfx/zoom.mp3 | Scroll-wheel zoom, Overview | scroll_003.ogg | Interface Sounds 1.0 by Kenney | CC0 1.0 | https://kenney.nl/assets/interface-sounds |
sfx/toggle.mp3 | Sound on, private toggle | toggle_002.ogg | Interface Sounds 1.0 by Kenney | CC0 1.0 | https://kenney.nl/assets/interface-sounds |
Kenney licence text: "License: (Creative Commons Zero, CC0) http://creativecommons.org/publicdomain/zero/1.0/ — free to use in personal, educational and commercial projects." Converted to mono MP3 with ffmpeg.
Computer voice made offline on 2026-10-08 with the open-source Piper text-to-speech engine (https://github.com/rhasspy/piper), voice en_US-kristin-medium (model card: trained on public-domain LibriVox recordings; dataset licence public domain — https://huggingface.co/rhasspy/piper-voices/tree/main/en/en_US/kristin/medium). Same voice family as the John Xuna slideshow.
Settings: length-scale 1.08, 0.35 s between sentences; loudness-normalised (−16 LUFS), 40 kbps mono MP3.
Scripts: narration-scripts.json (one clip per public chapter + intro). Private chapters have no narration.