Function roleOf

roleOf(pitch: number, chord: ChordData, chordId?: number): VoicedRole
Classify a pitch's harmonic role and lock level within a chord.

The role comes from the pitch's interval class above the chord root: root (0), third (3/4), fifth (6/7/8), seventh (10/11), and 9/11/13 tensions (2/5/9, and the flat ninth 1). The root locks the chord identity, the third locks its quality, and everything else is free voicing. In a suspended chord (a chord whose intervals include a 4th (5) or 2nd (2) but no third), the suspended tone takes the third's place as the quality-defining tone and is locked to quality, since moving it changes the chord. Detecting an octave doubling requires the surrounding voicing, which this single-pitch query does not carry, so doubling is part of the type but not returned here.
Parameters
- pitch: number
  MIDI pitch or bare pitch class.
- chord: ChordData
  The chord providing the root reference.
- chordId: number = 0
  Identifier stored on the result (defaults to 0).
Returns VoicedRole
The pitch's role, lock level, and owning chord id.
Example
```
import { roleOf, makeChord } from '@libraz/libcantus';
roleOf(64, makeChord(0, 'maj')); // E over C major
// { role: 'third', lock: 'quality', belongsToChordId: 0 }
```
- Defined in theory/harmony/index.ts:57