# Expedition 018

### 1. System name
Narrative Antiphon with Obligatory Closure

### 2. Pitch organization
Irrational-ratio tuning. Seven pitches per octave derived from 2^(k/7) with a golden-ratio-modulated perturbation (±0.8% from strict 7-EDO). Octave-repeating; two octaves used (16 pitches). The perturbation ensures no interval is a simple rational ratio — all intervals are *nearly-tempered but not quite*, producing a slightly unstable harmonic quality that the bell-strike at each phrase-end "locks" into resolution.

### 3. Rhythmic organization
Additive 4+4+3 at 300 ms (cycle 3.3 s). Silence is the piece's foundation — between phrases, long silences mark the narrative's breath. The bell-strike at each phrase-end is the grammar's *closure marker*; without it the next phrase cannot begin.

### 4. Formal structure
Through-composed narrative in five sections:
- **I. Opening** — choir L sings; silence; choir R answers; silence
- **II. Rising** — alternation faster, chord motion increases
- **III. Encounter** — choirs overlap briefly at the center of the piece, then separate
- **IV. Resolution** — choirs begin to sing the same chord material simultaneously
- **V. United** — both choirs on home chord, all eight voices together, final bell

The narrative is about the meeting of two bodies. It is not metaphor for anything outside the piece; the two choirs are the story.

### 5. Texture and voicing
Spectral cloud, antiphonal choirs. Two four-voice choirs (L and R) each moving as a homophonic body (voice independence near zero within each choir). Plus one ritual-punctuation bell that delivers the obligatory phrase-closure.

### 6. Ornament and inflection
Obligatory structural. Every phrase ends with a bell-strike on the upper-octave home and a collective downward slide (-45 cents) across the entire choir. This is not expressive ornament — it is the grammar's phrase-terminator. A phrase without closure is incomplete.

### 7. Performance context
Ritual-ceremonial; the two choirs stand in the space and the silence between them is what the listener attends to. The bell is sounded by a third participant — neither choir, but necessary to both.

### 8. Relationship to neighboring systems
Shares with **Aboriginal Australian song cycle** the through-composed narrative over long duration with silence as foundational. Shares with **Korean pansori** the narrative-storytelling function. Shares with **Japanese Noh** the ritual-ceremonial context and the restraint of ornament. The unique synthesis: *antiphonal narrative for two eight-voice choirs in irrational-ratio tuning where every phrase closure is a bell-locked resolution of the tuning's instability*.

### 9. Audio specification

```json
{
  "duration_seconds": 93.0,
  "pitch_system": {
    "encoding": "ratio",
    "reference_hz": 200,
    "pitches": [
      1.0,
      1.1129,
      1.2181,
      1.3352,
      1.4882,
      1.6534,
      1.8074,
      2.0,
      2.0,
      2.2258,
      2.4362,
      2.6705,
      2.9765,
      3.3069,
      3.6148,
      4.0
    ],
    "octave_repeats": true,
    "inflection_rules": [
      {
        "pitch_index": 0,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 1,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 2,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 3,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 4,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 5,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 6,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 7,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 8,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 9,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 10,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 11,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 12,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 13,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 14,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      },
      {
        "pitch_index": 15,
        "inflection_cents_range": [
          -45,
          0
        ],
        "direction": "down"
      }
    ]
  },
  "rhythm_system": {
    "type": "additive",
    "groupings": [
      4,
      4,
      3
    ],
    "base_unit_ms": 300
  },
  "voices": [
    {
      "name": "L1",
      "timbre": "vocal_male_low",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        -0.7,
        0.1
      ]
    },
    {
      "name": "L2",
      "timbre": "vocal_male_low",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        -0.6,
        0.1
      ]
    },
    {
      "name": "L3",
      "timbre": "reed",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        -0.49999999999999994,
        0.1
      ]
    },
    {
      "name": "L4",
      "timbre": "vocal_female_high",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        -0.3999999999999999,
        0.1
      ]
    },
    {
      "name": "R1",
      "timbre": "vocal_male_low",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        0.7,
        0.1
      ]
    },
    {
      "name": "R2",
      "timbre": "vocal_male_low",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        0.6,
        0.1
      ]
    },
    {
      "name": "R3",
      "timbre": "reed",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        0.49999999999999994,
        0.1
      ]
    },
    {
      "name": "R4",
      "timbre": "vocal_female_high",
      "pitch_indices": [
        0,
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15
      ],
      "rhythm_role": "sustained_drone",
      "amplitude": 0.55,
      "spatial_position": [
        0.3999999999999999,
        0.1
      ]
    },
    {
      "name": "bell",
      "timbre": "chimes",
      "pitch_indices": [
        7,
        14
      ],
      "rhythm_role": "ritual_punctuation",
      "amplitude": 0.6,
      "spatial_position": [
        0.0,
        0.4
      ]
    }
  ],
  "form": {
    "arc_type": "through_composed",
    "sections": [
      {
        "name": "I_opening",
        "start_seconds": 0,
        "duration_seconds": 15,
        "character": "L first, silence, R answers, silence",
        "chord_tones": [
          0,
          2,
          4,
          7
        ]
      },
      {
        "name": "II_rising",
        "start_seconds": 15,
        "duration_seconds": 20,
        "character": "faster alternation, chord motion",
        "chord_tones": [
          2,
          4,
          5,
          7
        ]
      },
      {
        "name": "III_encounter",
        "start_seconds": 35,
        "duration_seconds": 20,
        "character": "choirs overlap briefly, then separate",
        "chord_tones": [
          4,
          6,
          7,
          9
        ]
      },
      {
        "name": "IV_resolution",
        "start_seconds": 55,
        "duration_seconds": 20,
        "character": "choirs begin sharing chord material",
        "chord_tones": [
          0,
          2,
          4,
          7
        ]
      },
      {
        "name": "V_united",
        "start_seconds": 75,
        "duration_seconds": 18,
        "character": "both choirs on home chord",
        "chord_tones": [
          0,
          2,
          4
        ]
      }
    ]
  },
  "ornamentation": {
    "density": 0.15,
    "rule": "Obligatory structural ornament: every phrase ends with a bell-strike (struck_metal on upper-octave home) plus a collective downward slide of the choir (45 cents). Non-optional \u2014 a phrase without the bell is incomplete."
  },
  "auto_pedal": false,
  "events": [
    {
      "t": 1.0,
      "voice": "L1",
      "pitch_index": 0,
      "duration_seconds": 4.0,
      "amplitude": 0.6
    },
    {
      "t": 1.0,
      "voice": "L2",
      "pitch_index": 2,
      "duration_seconds": 4.0,
      "amplitude": 0.55
    },
    {
      "t": 1.0,
      "voice": "L3",
      "pitch_index": 4,
      "duration_seconds": 4.0,
      "amplitude": 0.5
    },
    {
      "t": 1.0,
      "voice": "L4",
      "pitch_index": 7,
      "duration_seconds": 4.0,
      "amplitude": 0.45
    },
    {
      "t": 4.6,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.6,
      "amplitude": 0.6
    },
    {
      "t": 8.0,
      "voice": "R1",
      "pitch_index": 1,
      "duration_seconds": 4.0,
      "amplitude": 0.58
    },
    {
      "t": 8.0,
      "voice": "R2",
      "pitch_index": 3,
      "duration_seconds": 4.0,
      "amplitude": 0.52
    },
    {
      "t": 8.0,
      "voice": "R3",
      "pitch_index": 5,
      "duration_seconds": 4.0,
      "amplitude": 0.48
    },
    {
      "t": 8.0,
      "voice": "R4",
      "pitch_index": 8,
      "duration_seconds": 4.0,
      "amplitude": 0.42
    },
    {
      "t": 11.6,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.6,
      "amplitude": 0.6
    },
    {
      "t": 16.0,
      "voice": "L1",
      "pitch_index": 2,
      "duration_seconds": 3.0,
      "amplitude": 0.6
    },
    {
      "t": 16.0,
      "voice": "L2",
      "pitch_index": 4,
      "duration_seconds": 3.0,
      "amplitude": 0.55
    },
    {
      "t": 16.0,
      "voice": "L3",
      "pitch_index": 5,
      "duration_seconds": 3.0,
      "amplitude": 0.5
    },
    {
      "t": 16.0,
      "voice": "L4",
      "pitch_index": 7,
      "duration_seconds": 3.0,
      "amplitude": 0.45
    },
    {
      "t": 18.6,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.5,
      "amplitude": 0.55
    },
    {
      "t": 20.5,
      "voice": "R1",
      "pitch_index": 0,
      "duration_seconds": 3.0,
      "amplitude": 0.6
    },
    {
      "t": 20.5,
      "voice": "R2",
      "pitch_index": 3,
      "duration_seconds": 3.0,
      "amplitude": 0.55
    },
    {
      "t": 20.5,
      "voice": "R3",
      "pitch_index": 5,
      "duration_seconds": 3.0,
      "amplitude": 0.5
    },
    {
      "t": 20.5,
      "voice": "R4",
      "pitch_index": 6,
      "duration_seconds": 3.0,
      "amplitude": 0.45
    },
    {
      "t": 23.1,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.5,
      "amplitude": 0.55
    },
    {
      "t": 25.0,
      "voice": "L1",
      "pitch_index": 3,
      "duration_seconds": 3.0,
      "amplitude": 0.6
    },
    {
      "t": 25.0,
      "voice": "L2",
      "pitch_index": 5,
      "duration_seconds": 3.0,
      "amplitude": 0.55
    },
    {
      "t": 25.0,
      "voice": "L3",
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      "duration_seconds": 3.0,
      "amplitude": 0.5
    },
    {
      "t": 25.0,
      "voice": "L4",
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      "duration_seconds": 3.0,
      "amplitude": 0.45
    },
    {
      "t": 27.6,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.5,
      "amplitude": 0.55
    },
    {
      "t": 29.5,
      "voice": "R1",
      "pitch_index": 1,
      "duration_seconds": 3.2,
      "amplitude": 0.62
    },
    {
      "t": 29.5,
      "voice": "R2",
      "pitch_index": 4,
      "duration_seconds": 3.2,
      "amplitude": 0.56
    },
    {
      "t": 29.5,
      "voice": "R3",
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      "duration_seconds": 3.2,
      "amplitude": 0.5
    },
    {
      "t": 29.5,
      "voice": "R4",
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      "amplitude": 0.45
    },
    {
      "t": 32.3,
      "voice": "bell",
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      "duration_seconds": 0.5,
      "amplitude": 0.58
    },
    {
      "t": 36.0,
      "voice": "L1",
      "pitch_index": 4,
      "duration_seconds": 4.5,
      "amplitude": 0.62
    },
    {
      "t": 36.0,
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      "duration_seconds": 4.5,
      "amplitude": 0.58
    },
    {
      "t": 36.0,
      "voice": "L3",
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      "duration_seconds": 4.5,
      "amplitude": 0.52
    },
    {
      "t": 36.0,
      "voice": "L4",
      "pitch_index": 9,
      "duration_seconds": 4.5,
      "amplitude": 0.46
    },
    {
      "t": 38.5,
      "voice": "R1",
      "pitch_index": 2,
      "duration_seconds": 4.0,
      "amplitude": 0.62
    },
    {
      "t": 38.5,
      "voice": "R2",
      "pitch_index": 5,
      "duration_seconds": 4.0,
      "amplitude": 0.58
    },
    {
      "t": 38.5,
      "voice": "R3",
      "pitch_index": 7,
      "duration_seconds": 4.0,
      "amplitude": 0.52
    },
    {
      "t": 38.5,
      "voice": "R4",
      "pitch_index": 10,
      "duration_seconds": 4.0,
      "amplitude": 0.46
    },
    {
      "t": 42.3,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.6,
      "amplitude": 0.6
    },
    {
      "t": 44.0,
      "voice": "L1",
      "pitch_index": 5,
      "duration_seconds": 4.0,
      "amplitude": 0.64
    },
    {
      "t": 44.0,
      "voice": "L2",
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      "duration_seconds": 4.0,
      "amplitude": 0.58
    },
    {
      "t": 44.0,
      "voice": "L3",
      "pitch_index": 8,
      "duration_seconds": 4.0,
      "amplitude": 0.52
    },
    {
      "t": 44.0,
      "voice": "L4",
      "pitch_index": 10,
      "duration_seconds": 4.0,
      "amplitude": 0.46
    },
    {
      "t": 47.0,
      "voice": "R1",
      "pitch_index": 3,
      "duration_seconds": 4.0,
      "amplitude": 0.64
    },
    {
      "t": 47.0,
      "voice": "R2",
      "pitch_index": 6,
      "duration_seconds": 4.0,
      "amplitude": 0.58
    },
    {
      "t": 47.0,
      "voice": "R3",
      "pitch_index": 8,
      "duration_seconds": 4.0,
      "amplitude": 0.52
    },
    {
      "t": 47.0,
      "voice": "R4",
      "pitch_index": 11,
      "duration_seconds": 4.0,
      "amplitude": 0.46
    },
    {
      "t": 51.0,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.6,
      "amplitude": 0.6
    },
    {
      "t": 56.0,
      "voice": "L1",
      "pitch_index": 0,
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      "amplitude": 0.6
    },
    {
      "t": 56.0,
      "voice": "L2",
      "pitch_index": 2,
      "duration_seconds": 4.0,
      "amplitude": 0.55
    },
    {
      "t": 56.0,
      "voice": "L3",
      "pitch_index": 4,
      "duration_seconds": 4.0,
      "amplitude": 0.5
    },
    {
      "t": 56.0,
      "voice": "L4",
      "pitch_index": 7,
      "duration_seconds": 4.0,
      "amplitude": 0.45
    },
    {
      "t": 56.0,
      "voice": "R1",
      "pitch_index": 0,
      "duration_seconds": 4.0,
      "amplitude": 0.55
    },
    {
      "t": 56.0,
      "voice": "R2",
      "pitch_index": 2,
      "duration_seconds": 4.0,
      "amplitude": 0.5
    },
    {
      "t": 56.0,
      "voice": "R3",
      "pitch_index": 4,
      "duration_seconds": 4.0,
      "amplitude": 0.45
    },
    {
      "t": 56.0,
      "voice": "R4",
      "pitch_index": 7,
      "duration_seconds": 4.0,
      "amplitude": 0.4
    },
    {
      "t": 60.1,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.7,
      "amplitude": 0.55
    },
    {
      "t": 62.5,
      "voice": "L1",
      "pitch_index": 1,
      "duration_seconds": 4.0,
      "amplitude": 0.58
    },
    {
      "t": 62.5,
      "voice": "L2",
      "pitch_index": 3,
      "duration_seconds": 4.0,
      "amplitude": 0.53
    },
    {
      "t": 62.5,
      "voice": "L3",
      "pitch_index": 5,
      "duration_seconds": 4.0,
      "amplitude": 0.48
    },
    {
      "t": 62.5,
      "voice": "L4",
      "pitch_index": 8,
      "duration_seconds": 4.0,
      "amplitude": 0.43
    },
    {
      "t": 62.5,
      "voice": "R1",
      "pitch_index": 1,
      "duration_seconds": 4.0,
      "amplitude": 0.55
    },
    {
      "t": 62.5,
      "voice": "R2",
      "pitch_index": 3,
      "duration_seconds": 4.0,
      "amplitude": 0.5
    },
    {
      "t": 62.5,
      "voice": "R3",
      "pitch_index": 5,
      "duration_seconds": 4.0,
      "amplitude": 0.45
    },
    {
      "t": 62.5,
      "voice": "R4",
      "pitch_index": 8,
      "duration_seconds": 4.0,
      "amplitude": 0.4
    },
    {
      "t": 66.6,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.7,
      "amplitude": 0.55
    },
    {
      "t": 69.0,
      "voice": "L1",
      "pitch_index": 0,
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      "amplitude": 0.6
    },
    {
      "t": 69.0,
      "voice": "L2",
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      "duration_seconds": 4.5,
      "amplitude": 0.55
    },
    {
      "t": 69.0,
      "voice": "L3",
      "pitch_index": 5,
      "duration_seconds": 4.5,
      "amplitude": 0.5
    },
    {
      "t": 69.0,
      "voice": "L4",
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      "duration_seconds": 4.5,
      "amplitude": 0.45
    },
    {
      "t": 69.0,
      "voice": "R1",
      "pitch_index": 0,
      "duration_seconds": 4.5,
      "amplitude": 0.55
    },
    {
      "t": 69.0,
      "voice": "R2",
      "pitch_index": 3,
      "duration_seconds": 4.5,
      "amplitude": 0.5
    },
    {
      "t": 69.0,
      "voice": "R3",
      "pitch_index": 5,
      "duration_seconds": 4.5,
      "amplitude": 0.45
    },
    {
      "t": 69.0,
      "voice": "R4",
      "pitch_index": 7,
      "duration_seconds": 4.5,
      "amplitude": 0.4
    },
    {
      "t": 73.6,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.7,
      "amplitude": 0.55
    },
    {
      "t": 77.0,
      "voice": "L1",
      "pitch_index": 0,
      "duration_seconds": 5.5,
      "amplitude": 0.55
    },
    {
      "t": 77.0,
      "voice": "L2",
      "pitch_index": 2,
      "duration_seconds": 5.5,
      "amplitude": 0.5
    },
    {
      "t": 77.0,
      "voice": "L3",
      "pitch_index": 4,
      "duration_seconds": 5.5,
      "amplitude": 0.45
    },
    {
      "t": 77.0,
      "voice": "L4",
      "pitch_index": 7,
      "duration_seconds": 5.5,
      "amplitude": 0.42
    },
    {
      "t": 77.0,
      "voice": "R1",
      "pitch_index": 0,
      "duration_seconds": 5.5,
      "amplitude": 0.52
    },
    {
      "t": 77.0,
      "voice": "R2",
      "pitch_index": 2,
      "duration_seconds": 5.5,
      "amplitude": 0.48
    },
    {
      "t": 77.0,
      "voice": "R3",
      "pitch_index": 4,
      "duration_seconds": 5.5,
      "amplitude": 0.43
    },
    {
      "t": 77.0,
      "voice": "R4",
      "pitch_index": 7,
      "duration_seconds": 5.5,
      "amplitude": 0.4
    },
    {
      "t": 82.7,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 0.9,
      "amplitude": 0.65
    },
    {
      "t": 84.5,
      "voice": "L1",
      "pitch_index": 0,
      "duration_seconds": 5.5,
      "amplitude": 0.5
    },
    {
      "t": 84.5,
      "voice": "L2",
      "pitch_index": 2,
      "duration_seconds": 5.5,
      "amplitude": 0.45
    },
    {
      "t": 84.5,
      "voice": "L3",
      "pitch_index": 4,
      "duration_seconds": 5.5,
      "amplitude": 0.4
    },
    {
      "t": 84.5,
      "voice": "L4",
      "pitch_index": 0,
      "duration_seconds": 5.5,
      "amplitude": 0.55
    },
    {
      "t": 84.5,
      "voice": "R1",
      "pitch_index": 0,
      "duration_seconds": 5.5,
      "amplitude": 0.48
    },
    {
      "t": 84.5,
      "voice": "R2",
      "pitch_index": 2,
      "duration_seconds": 5.5,
      "amplitude": 0.43
    },
    {
      "t": 84.5,
      "voice": "R3",
      "pitch_index": 4,
      "duration_seconds": 5.5,
      "amplitude": 0.4
    },
    {
      "t": 84.5,
      "voice": "R4",
      "pitch_index": 0,
      "duration_seconds": 5.5,
      "amplitude": 0.5
    },
    {
      "t": 90.1,
      "voice": "bell",
      "pitch_index": 7,
      "duration_seconds": 1.2,
      "amplitude": 0.68
    }
  ]
}
```

### 10. Field note
The bell is the only pitch heard in both choirs. Its ring is what makes them one piece instead of two.