human-experience-filter-art/docs/audio-candidate-pool.md

Audio candidate pool — rotating pools per altitude (2026-06-26)

Candidate soundtrack/ambience for the "audio + video" setting. Following operator feedback, each altitude now has a rotating pool (mirrors the video Scale.pool model — random pick per landing, or pairable per-clip).

Two audio layers per altitude (operator, 2026-06-26)

The "audio + video" setting layers two kinds of audio per altitude:

1. Ambience / audio track — the soundscape (waves, reef crackle, chorus, etc.). This is what we're sourcing now.
2. Music track — a separate composed musical layer. Shipped (2026-07-01) as the Audio-dropdown "Music" option: unlike the earlier per-altitude idea, it is now one single ethereal loop played the same at every altitude (see § Music below).

Pools below are the ambience layer unless marked music. Distinction (operator): the ambience/soundtrack layer is an environmental, real-world soundscape (waves, reef, whale, room-tone hum) — not composed music. A musical pad/track, however nice, belongs in the music layer, even for "atmospheric" altitudes like cosmos/orbit.

Media is gitignored (simulator/sample_media/**/*.{wav,mp3,…}); this file is the re-sourceable record. Files: simulator/sample_media/audio/<altitude>/<name>.<ext>, served at /media/audio/<altitude>/<name>.<ext>. Review gallery (gitignored): simulator/static/review_audio.html → /review_audio.html with the sim running.

Round-2 feedback applied (operator, session 2026-06-26)

• abyss ✓ kept (blue-whale moan) · coast ✓ kept (waves + terns)
• cosmos ✗ plasma static "hurt my ears" → replaced with 3 NASA sonifications
• orbit ✗ whistlers "sound like lasers" → replaced with gentle Earth chorus (+ wind)
• reef ✗ "shouldn't have whales (too deep for a reef)" → whale removed; now crackle + diver
• Operator: "try all three… rotation of audio like the video, or per-video audio track."

Design arc

Descending the dial is one journey: cosmos & abyss = vast/dark/sparse siblings; coast = warm human middle; orbit & reef = transitional membranes. The science recordings (NASA/NOAA) keep the "machines reshaping perception" thesis literal.

Pools

altitude	id	clip	source	dur	license
🌌 cosmos	cosmos/pillars	✓ KEEP — Pillars of Creation (M16), twinkly sweep	NASA/CXC/SAO — https://chandra.si.edu/sound/m16.html (sounds/m16_all.mp4)	30s	PD (NASA, credit)
🌌 cosmos	cosmos/music	🎵 music track — TBD (deferred). Black-hole drone DROPPED (too creepy, not awe-inspiring); Galactic Center dropped earlier	—	—	—
🛰 orbit	orbit/spaceamb	✓ KEEP — station room-tone hum ("inside the orbiting craft")	Sonicfreak — https://freesound.org/s/174450/ (cdn.freesound.org/previews/174/174450_746632-hq.mp3)	2:31	CC0
🛰 (music)	deferred	🎵 "Frozen Star" warm pad — moved to MUSIC layer (it's music, not ambience)	Kevin MacLeod / incompetech — https://incompetech.com/music/royalty-free/mp3-royaltyfree/Frozen%20Star.mp3	3:41	CC-BY
🐠 reef	reef/soundscape	✓ richer reef (round 4) — 6-layer bake: submerged underwater bed (bubbles/sloosh) + shrimp crackle + fish chorus + toadfish + grouper + damselfish	NOAA SanctSound (FK+GR *_snappingshrimp_*, FK02_01_fishchorus, GR01_01_toadfish, FK03_01_redgrouper, PM05_01_damselfish) + DCSFX "Underwater [Loop] AMB" https://freesound.org/s/366159/ (cdn.freesound.org/previews/366/366159_6725579-hq.mp3); loop-to-60 + amix + dynaudnorm	60s	PD (NOAA) + CC0 (underwater)
🏖 coast	coast/waves	Sea waves + tern calls	BigSoundBank #0267 — https://bigsoundbank.com/sea-waves-and-seagulls-s0267.html (/UPLOAD/mp3/0267.mp3)	57s	CC0
🕳 abyss	abyss/whale	NE Pacific blue-whale "AB call"	NOAA PMEL — https://www.pmel.noaa.gov/acoustics/multimedia/NETS_bluWhale.wav	13s	PD (NOAA)

Music (the Audio-dropdown "Music" option)

SUPERSEDED 2026-07-02: the single ethereal loop below was replaced by a rotating crossfading playlist of mellow drumless synth (Kevin MacLeod, CC BY) — see docs/music-candidate-pool.md. The ethereal-loop record is kept for history.

(history) ethereal loop — shipped 2026-07-01, then replaced

One ethereal ambient loop, played the same at every altitude (altitude-independent — NOT the per-altitude idea the "cosmos/music" / "Frozen Star" rows above reserved; those stay as historical candidates). The operator's brief: ethereal, relaxing — like innerflo.me. CC0 (operator's sourcing choice), so attribution is courtesy, not required.

id	clip	source	dur	license
music/ethereal	✓ KEEP — "Ambient F Sharp Minor Ethereal Choir Pad 1": blurry, paulstretched layered choir — "peaceful, magical, soothing"	deadrobotmusic — https://freesound.org/people/deadrobotmusic/sounds/808032/ (hq preview: cdn.freesound.org/previews/808/808032_*-hq.mp3)	3:38	CC0

Production: simulator/build_audio_media.py SOURCES["music"] → seamless loudness-normalized loop at audio/music/ethereal.loop.mp3, served /media/audio/music/ethereal.loop.mp3 (client fallback: app.js MUSIC_FALLBACK). Download the sound page's WAV/MP3 to simulator/sample_media/audio/music/ethereal.mp3, then python simulator/build_audio_media.py.

Sourcing rule (learned 2026-06-26)

Source only from a browsable page the operator can open and whose license is stated. The Mixkit clips were pulled by raw CDN asset id (assets.mixkit.co/.../<id>-preview.mp3) with no findable catalog page — operator couldn't see them, so they were removed. Good hubs: NASA SVS / Chandra, NOAA PMEL/SanctSound (PD), BigSoundBank (CC0), Pixabay (visible license). Avoid asset-id grabs and ND/NC licenses.

Open items / next pass

• orbit — ✅ SETTLED: orbit/spaceamb (Sonicfreak station room-tone hum, CC0). Rejected en route: laser whistlers, Earth chorus, plain wind, "Frozen Star" pad (music). A real NASA ISS recording (Hadfield "Space Station Noise", SoundCloud) remains the authentic upgrade if ever wanted — needs a harder fetch (no yt-dlp; brew install denied).
• ambience layer COMPLETE — all 5 picked: cosmos/pillars · orbit/spaceamb · coast/waves · reef/soundscape · abyss/whale. Next is the production pass + wiring (below) and the music layer.
• reef — ✅ round-4 6-layer bake (reef/soundscape): NOAA PD biological layers + a CC0 submerged underwater "you're under" bed (DCSFX freesound #366159, hq preview). License clean. SanctSound clips: files/SanctSound_*.mp4 at https://sanctsound.ioos.us/files/ (extract audio).
• music layer — ✅ SHIPPED 2026-07-01 as the Audio-dropdown "Music" option, but as ONE altitude-independent ethereal loop (music/ethereal, CC0), not the per-altitude track once envisioned. See § Music above. (The cosmos/music / "Frozen Star" rows are now historical per-altitude candidates, not planned work.)
• Production (after picks): loop seams, length normalization, cross-altitude crossfade (mirror video); cosmos/abyss clips are short → loop.

Re-download / re-bake

A=simulator/sample_media/audio; FF=$(python -c "import imageio_ffmpeg;print(imageio_ffmpeg.get_ffmpeg_exe())")
mkdir -p $A/cosmos $A/orbit $A/reef $A/coast $A/abyss
# NASA sonifications (mp4 -> mp3)
for u in perseus_sonification:blackhole m16_all:pillars galactic_all:galaxy; do
  f=${u%%:*}; o=${u##*:}; curl -fsSL "https://chandra.si.edu/sound/sounds/$f.mp4" -o /tmp/$o.mp4
  "$FF" -y -i /tmp/$o.mp4 -vn -q:a 4 $A/cosmos/$o.mp3; done
curl -fsSL "https://svs.gsfc.nasa.gov/vis/a010000/a011000/a011073/Earthsong-540-MASTER_high.mp4" -o /tmp/es.mp4
"$FF" -y -i /tmp/es.mp4 -vn -q:a 4 $A/orbit/earthsong.mp3
curl -fsSL "https://assets.mixkit.co/active_storage/sfx/1162/1162-preview.mp3" -o $A/orbit/wind.mp3
curl -fsSL "https://www.nhm.ac.uk/content/dam/nhm-www/discover/audio/sound-of-coral-reef.mp3" -o $A/reef/crackle.mp3
curl -fsSL "https://assets.mixkit.co/active_storage/sfx/1242/1242-preview.mp3" -o $A/reef/scuba.mp3
curl -fsSL "https://bigsoundbank.com/UPLOAD/mp3/0267.mp3" -o $A/coast/waves.mp3
curl -fsSL "https://www.pmel.noaa.gov/acoustics/multimedia/NETS_bluWhale.wav" -o $A/abyss/whale.wav
# layered reef
"$FF" -y -i $A/reef/crackle.mp3 -i $A/reef/scuba.mp3 \
  -filter_complex "[1:a]volume=0.55[s];[0:a][s]amix=inputs=2:duration=first,dynaudnorm" -q:a 4 $A/reef/layered.mp3