{
  "schemaVersion": 1,
  "fixtureId": "audio-filter-biquad-synthetic-v1",
  "performedAt": "2026-08-26",
  "generator": "scripts/reproduce-audio-filter-evidence.mjs",
  "environment": {
    "runtime": "v22.22.2",
    "platform": "darwin-arm64",
    "implementation": "deterministic JavaScript Float64 RBJ biquad"
  },
  "input": {
    "rights": "Mathematically generated sine waves; no third-party audio is used.",
    "sampleRate": 48000,
    "durationSeconds": 1,
    "measurementStartSeconds": 0.25,
    "amplitude": 0.25,
    "frequenciesHz": [100, 1000, 8000]
  },
  "filters": {
    "cutoffHz": 1000,
    "q": 0.70710678,
    "types": ["high-pass", "low-pass"]
  },
  "measurements": {
    "highPass": [
      {
        "frequencyHz": 100,
        "inputRms": 0.176777,
        "outputRms": 0.001763,
        "gainDb": -40.025
      },
      {
        "frequencyHz": 1000,
        "inputRms": 0.176777,
        "outputRms": 0.125,
        "gainDb": -3.01
      },
      {
        "frequencyHz": 8000,
        "inputRms": 0.176777,
        "outputRms": 0.176762,
        "gainDb": -0.001
      }
    ],
    "lowPass": [
      {
        "frequencyHz": 100,
        "inputRms": 0.176777,
        "outputRms": 0.176768,
        "gainDb": 0
      },
      {
        "frequencyHz": 1000,
        "inputRms": 0.176777,
        "outputRms": 0.125,
        "gainDb": -3.01
      },
      {
        "frequencyHz": 8000,
        "inputRms": 0.176777,
        "outputRms": 0.002278,
        "gainDb": -37.797
      }
    ]
  },
  "checks": [
    {
      "id": "high-pass-rejects-low-band",
      "assertion": "100 Hz high-pass gain is at most -35 dB",
      "observed": "-40.025 dB",
      "pass": true
    },
    {
      "id": "high-pass-preserves-high-band",
      "assertion": "8 kHz high-pass gain is at least -0.5 dB",
      "observed": "-0.001 dB",
      "pass": true
    },
    {
      "id": "low-pass-preserves-low-band",
      "assertion": "100 Hz low-pass gain is at least -0.5 dB",
      "observed": "0 dB",
      "pass": true
    },
    {
      "id": "low-pass-rejects-high-band",
      "assertion": "8 kHz low-pass gain is at most -30 dB",
      "observed": "-37.797 dB",
      "pass": true
    },
    {
      "id": "cutoff-is-minus-three-db",
      "assertion": "Both filters are between -3.2 dB and -2.8 dB at 1 kHz",
      "observed": "high-pass -3.01 dB, low-pass -3.01 dB",
      "pass": true
    }
  ],
  "result": {
    "pass": true,
    "sha256": "ad7512e0b0aea2801e4050f0756025d818ce5a06bef46815c3b2bd8731a9b7a9"
  },
  "limitations": [
    "This fixture verifies the numerical frequency response of one second-order biquad implementation only.",
    "It does not prove subjective sound quality, DAW plug-in behavior, phase suitability, or settings for every recording.",
    "The synthetic input cannot replace listening checks with the reader's own source material and monitoring chain."
  ]
}