{
  "version": 1,
  "updatedAt": "2026-10-11",
  "species": {
    "commonName": "American crow",
    "scientificName": "Corvus brachyrhynchos"
  },
  "lesson": {
    "id": "first-listen",
    "version": 1,
    "url": "https://crowlingo.org/learn/first-listen",
    "comparisonUrl": "https://crowlingo.org/learn/caw-and-rattle",
    "status": "Starter preview; no acoustic skill score or validated held-out assessment.",
    "estimatedMinutes": 2
  },
  "derivation": {
    "tool": "ffmpeg version 8.1.2 Copyright (c) 2000-2026 the FFmpeg developers",
    "method": "First eight seconds; mono 16 kHz PCM, then 48 kbit/s MP3. Spectrogram generated from that MP3 with a Hann window, linear 0–8 kHz frequency axis, logarithmic intensity, fixed 80 dB range below 0 dBFS, gain 1 and viridis palette. Sound pictures use 640×160 pixels and WebP quality 60. No volume normalization. Recording levels differ, so colour brightness is not a calibrated loudness comparison.",
    "command": "node scripts/gen-learning-media.mjs"
  },
  "clips": [
    {
      "id": "clip-a",
      "recording": "corvus-brachyrhynchos-call",
      "start": 0,
      "label": "American crow call",
      "observation": "The source identifies this as an American crow call. Compare the spaces between sounds; the description does not identify the bird’s intent.",
      "audio": "/learning/clip-a.mp3",
      "spectrogram": "/learning/clip-a.webp",
      "startSec": 0,
      "endSec": 8,
      "durationSec": 8,
      "sourceAudio": "/audio/atlas/corvus-brachyrhynchos-call.ogg",
      "sourceTitle": "Corvus brachyrhynchos call.ogg",
      "sourceUrl": "https://commons.wikimedia.org/wiki/File%3ACorvus%20brachyrhynchos%20call.ogg",
      "attribution": "United States Geological Survey",
      "license": "Public domain",
      "licenseUrl": "https://en.wikipedia.org/wiki/Public_domain",
      "sourceDescription": "Call of Corvus brachyrhynchos (American Crow)",
      "reviewStatus": "Source metadata checked; excerpt listening and answer-key review pending.",
      "audioBytes": 48861,
      "spectrogramBytes": 22474,
      "sourceSha256": "899805a5b2bfd2e9c871175a328f4d97a191f49e17616f8dcf3bb204f5ce9bb4",
      "audioSha256": "4c1c5991140753e5a9dd690ed5406b1b4c42beb24d5cb810a7097fc0eea5563d",
      "spectrogramSha256": "8309132793baf7d38cd438a013124e16f1ee5c09f685e2c5ea35fb749a6a8793"
    },
    {
      "id": "clip-b",
      "recording": "american-crow",
      "start": 0,
      "label": "Typical call, described by the recordist",
      "observation": "The recordist describes a typical American crow call, recorded with a parabolic microphone. Differences in recording equipment can change what you hear.",
      "audio": "/learning/clip-b.mp3",
      "spectrogram": "/learning/clip-b.webp",
      "startSec": 0,
      "endSec": 8,
      "durationSec": 8,
      "sourceAudio": "/audio/atlas/american-crow.ogg",
      "sourceTitle": "American Crow.ogg",
      "sourceUrl": "https://commons.wikimedia.org/wiki/File%3AAmerican%20Crow.ogg",
      "attribution": "G McGrane",
      "license": "Public domain",
      "licenseUrl": "https://en.wikipedia.org/wiki/Public_domain",
      "sourceDescription": "Typical American Crow call.  Recorded with parabolic mike.",
      "reviewStatus": "Source metadata checked; excerpt listening and answer-key review pending.",
      "audioBytes": 48861,
      "spectrogramBytes": 24848,
      "sourceSha256": "b880c85505e711a5a6f0bf04ebee72dfcefb067017b55de376b1a6d57e46bad5",
      "audioSha256": "5b1d854d256f734c6fc06893c68c810f657e4042ff8e075337162009faff236a",
      "spectrogramSha256": "33456499bc643a7ac6c813954b292c7e612c3bfb901149b0354aea43d394821e"
    },
    {
      "id": "clip-c",
      "recording": "xc115429",
      "start": 0,
      "label": "Rattling calls, described by the recordist",
      "observation": "The recordist describes soft rattling calls at about ten metres from the microphone. Their note mentions a coo around 27 seconds in the full recording; that part is outside this excerpt.",
      "audio": "/learning/clip-c.mp3",
      "spectrogram": "/learning/clip-c.webp",
      "startSec": 0,
      "endSec": 8,
      "durationSec": 8,
      "sourceAudio": "/audio/atlas/xc115429.mp3",
      "sourceTitle": "Corvus brachyrhynchos - American Crow XC115429.mp3",
      "sourceUrl": "https://commons.wikimedia.org/wiki/File%3ACorvus%20brachyrhynchos%20-%20American%20Crow%20XC115429.mp3",
      "attribution": "Jonathon Jongsma",
      "license": "CC BY-SA 3.0",
      "licenseUrl": "https://creativecommons.org/licenses/by-sa/3.0",
      "sourceDescription": ":Soft rattling calls given at approximately 10m from microphone, and at least one 'coo' sound around 0:27.",
      "reviewStatus": "Source metadata checked; excerpt listening and answer-key review pending.",
      "audioBytes": 49342,
      "spectrogramBytes": 27602,
      "sourceSha256": "82189f8b67c429a46415395f62ba7c57bbab6a6f7632a374eaf814bd2d2cea2a",
      "audioSha256": "96ca3dcab781c54a36eb83fa3b4be65cfb4872deaa765740c741c15ff1049e91",
      "spectrogramSha256": "48907b10112f0c8cc6dcf7c2a5818ca4ee6a5eb07393b078d2e345d7081c2f46"
    }
  ]
}