A cappella just intonation makes a group’s overall pitch drift across key modulations

Evidence

When singing a cappella, though, there is no requirement to stick to equal tempered tuning, and the possibility exists for singers to make use of the more consonant just intonation where the intervals are maximally consonant (see Section 3.3.3), for example with perfect fifths (frequency ratio 3:2) and just major and minor thirds (frequency ratios 5:4 and 6:5, respectively). Bearing in mind that just intonation cannot be used to tune a 12-note chromatic musical keyboard if the octaves are to remain in the ratio 2:1 (see Section 3.4), there could be musical situations in which singing in just intonation causes the overall pitch to drift as a piece modulates through different keys and back to the starting key. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1376

This experiment confirms that singers do tend toward just tuning and that they maintain this overall tuning even at the expense of the overall pitch of the piece. Thus a dichotomy is presented to choral singers and their conductors in terms of whether to keep the overall pitch in tune and make some compromise to the tuning of individual chords or whether to allow the overall pitch to drift. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1387

Categorization

Category: Causal Relationships

• QUESTION: Does a cappella pitch drift actually accumulate in practice, or do singers unconsciously correct toward the opening key? The author’s experiment (Howard 2007a) apparently tests this.
• XREF: Directly extends the equal-tempered vs just-intonation tradeoff established earlier in the book (Sections 3.3.3, 3.4); also connects to the piano’s forced compromise from previous chapters.

Related

• Singing in just intonation causes pitch drift when modulating through keys (similarity 0.92)
• Vocal quartets empirically drift flat as just intonation predicts (similarity 0.87)
• Just-tuned chord progressions predict key drift of a full semitone (similarity 0.85)
• Singing just-tuned chords predicts rapid pitch drift flat (similarity 0.83)
• A capella groups can adopt just intonation, causing overall pitch to drift through keys (similarity 0.82)

Broader Connections

• A capella groups can adopt just intonation, causing overall pitch to drift through keys #expands (0.95) — David Howard, Jamie Angus, coustics and Psychoacoustics, 1389
• Vocal quartets empirically drift flat as just intonation predicts #corroborates (0.92) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1382