{
  "version": "impact20",
  "date": "2026-10-14",
  "scope": "Archive/source verification and waveform analysis, not listening or physical nuclear-sound reconstruction.",
  "nuclear_archive_audit": [
    {
      "institution": "Lawrence Livermore National Laboratory",
      "title": "Preserving the Past to Protect the Future, Science & Technology Review Oct/Nov 2017",
      "url": "https://str.llnl.gov/sites/str/files/2024-04/10.17.pdf",
      "article_url": "https://str.llnl.gov/past-issues/octobernovember-2017/preserving-past-protect-future",
      "checked": "Official PDF downloaded and extracted; original subsection title is Silent Films Speak Volumes. Describes digitizing historic measurement films and extracting optical blast dimensions.",
      "sound_status": "These scientific films are presented as silent; no synchronized blast recording or audio asset was established. This does not claim all historical nuclear films are silent.",
      "usage": "Historical/reference evidence only; no footage or audio incorporated."
    },
    {
      "institution": "Imperial War Museums Film Archive",
      "title": "NUCLEAR EXPLOSIONS: AIR BURST, DRN 1203",
      "url": "https://film.iwmcollections.org.uk/record/39069",
      "checked": "Primary archive catalogue explicitly lists Sound format: Silent for this particular record.",
      "sound_status": "Silent. Cannot be used as a real nuclear sound source.",
      "usage": "Metadata only; no archival media copied."
    },
    {
      "institution": "U.S. Department of Energy / NARA",
      "title": "Atomic Energy Commission Films Available Online",
      "url": "https://www.energy.gov/lm/atomic-energy-commission-films-available-online",
      "checked": "Official catalogue links AEC films to NARA and describes edited educational/documentary productions, including Atomic Tests in Nevada.",
      "sound_status": "The descriptions do not establish which blast tracks, if any, were recorded live in sync versus added in editing. No synchronized nuclear recording was verified.",
      "usage": "Catalogue read only; no unverified soundtrack extracted."
    }
  ],
  "conclusion": "A usable authentic synchronized nuclear blast recording with confirmed provenance/reuse status was not obtained. The game does not label its sound as an actual nuclear recording. It uses an explicitly non-nuclear field-recorded transient plus designed low-mid body and long synthesis.",
  "game_audio_sources": [
    {
      "title": "Explosion #2, sound1808",
      "author": "Joseph SARDIN / BigSoundBank",
      "url": "https://bigsoundbank.com/explosion-2-s1808.html",
      "license_url": "https://bigsoundbank.com/licenses.html",
      "license": "CC0 1.0 Universal; editing/commercial game distribution permitted by the author",
      "identity": "Outdoor agricultural gas-cannon sound recorded approximately10m away, not nuclear.",
      "file": "assets/audio/blast-transient.wav",
      "processing_and_analysis": "audio-blast-source.json",
      "downloaded": true,
      "listened": false
    },
    {
      "title": "Drill #791",
      "author": "Joseph SARDIN / BigSoundBank",
      "url": "https://bigsoundbank.com/perceuse-filaire-s0791.html",
      "license": "CC0",
      "identity": "Existing liked wood-drilling loop, unchanged",
      "file": "assets/audio/drill-loop.wav",
      "preservation": "audio-drill-preservation.json confirms original WAV and seven drill/noise/destruction functions are byte-identical to v19."
    }
  ],
  "implementation": {
    "countdown": "One dry45ms triangle tick at180→145Hz per number. No speech, siren, whistle. Legacy nuke-fall key returnsfalse without creating a source even if a sample override is registered.",
    "timeline": "UI host: tick3at0s,2at1s,1at2s; silent drop3–6s; impactat6s; aftermath7.3s. Preview follows the same sequence.",
    "bat": "Ring shortened to140/95ms and reduced to720/1200Hz at lower gains; short185→90Hz contact plus high-pass crack and160ms crunch. Five hit layers plus up to seven rubble layers stay within12.",
    "nuke": "One optional real non-nuclear transient plus eight synthetic layers: sharp crack,215→105Hz and125→82Hz body for low-mid presence,52→30Hz bass, broad pressure body and staggered rolling noise. Body envelopes retain32% to72% of duration. Last decay ends about5.76s after impact. Maximum9sources, or12with the protected3-source drill.",
    "loading": "loadImpactSample() independently fetches/decodes local WAV once. Failure returnsfalse and preserves synthesis. No auto playback or swap during an impact; dispose aborts/ignores late load or decode. Existing drill loader is unchanged.",
    "relative_levels": "audio-levels.json provides source-envelope bounds and PCM component statistics only, not measured output loudness or listening validation."
  },
  "limits": [
    "No authentic nuclear detonation waveform was used or claimed.",
    "Conventional transient identity is deliberately documented.",
    "Waveform/FFT analysis and automated lifecycle checks cannot judge subjective grandeur, device bass response or audible balance.",
    "No browser playback, microphone recording or direct listening was performed."
  ],
  "credit": "Additional field recordings: Joseph SARDIN – BigSoundBank.com (CC0)."
}