Analysis of Intonation in Unison Choir Singing

Helena Cuesta1, Emilia Gómez1,2, Agustín Martorell1, Felipe Loáiciga1

Singers synchronize their pitch and timing when performing together in a choir. In this work we analyze several expressive characteristics of choir singing, with special emphasis on unison performances, to study how singers blend together and interact with each other in terms of f0 dispersion, intonation, and vibrato.

SUMMARY

BACKGROUND CHORAL-SINGING DATASET

METHODOLOGY

• Choir vs. solo singing: voices of a choir blend together.

• Agreement between all voice sources: degree of unison.

• f0 dispersion: to what extent singers of an unison agree to

each other in terms of pitch.

• Intonation: accuracy of pitch in singing with respect to a specific tuning system.

• Vibrato is a periodic oscillation in pitch and is very relevant in singing voice.


RESULTSF0 DISPERSION

• Dispersion (per window) between 16 and 30 cents, similar to results by Jers & Ternström: 25-30 cents.

• Basses have the highest dispersion / sopranos have the lowest.

• The most difficult piece has the highest dispersion.

INTONATION CORRELATION• Intonation correlation oscillates.

VIBRATO ANALYSIS• Vibrato rate average is 5.13 Hz, std is 0.26 Hz.

• Vibrato amplitude average is 92.12 cents, std is

12.45 cents. No specific patterns found.

CONCLUSIONS• Characterize unison by mean pitch and f0 dispersion. The larger the dispersion, the smaller the degree of unison.

• Singers’ intonation is affected by other singers’ performance. Results suggest that although intonation adjustments are not systematic

nor constant, there is some correlation between them.

• Singers have training, but they are not professionals: they do not have the complete control of their vibrato.

• We require more data to analyze the correlation of the intonation and the vibrato.

1Music Technology Group, Universitat Pompeu Fabra , Barcelona (Spain) 2Joint Research Centre, European Commission, Seville (Spain)

helena.cuesta@upf.edu

http://doi.org/10.5281/zenodo.1286570

• Record 16 singers from the Anton Bruckner Choir (Barcelona).

• 4 singers/section (SATB), individual close microphones. Video of the conductor.

• Locus Iste by Anton Bruckner (Latin), Niño Dios by Francisco Guerrero (Spanish), El Rossinyol, popular (Catalan).

f0 dispersion analysis

intonation synchronization

vibrato synchronization

audio recordings

MIDI files

manual audio-MIDI alignment

f0 estimation using SAC

…

f0 tr

ajec

torie

s

note segmentation

Singers adjust intonation to

others

for each section (unison)

Derivatives of the pitch

trajectories

Pearson correlation

Percentage of vibrato

Vibrato frequency and

extent

Vibrato correlation

Std of f0 trajectories

Expressed in cents

• Max. average correlation = 0.34±0.015 (tenors).

• Lowest correlations found in the bass section.

• Tenors 1-2 obtain the highest average

correlation (0.36±0.07). Sopranos 2-3 obtain the highest instantaneous correlation (0.88). • < 50% of the notes have vibrato.