Intonation precision of choir singers
Sten Ternström, Johan Sundberg · The Journal of the Acoustical Society of America · 1988
Results from two experimental investigations on the acoustics of choirs are reported. The first concerns sound-pressure levels (SPL) inside choirs, and the balance of loudness between a singer’s own voice and the ‘‘reference’’ sound from the rest of the choir. Long-term SPL averages during rehearsals typically gave 80–100 dB, with little variation between choirs or with position in the choir. The fundamental frequency precision of choir singers was found to deteriorate abruptly when the reference was too loud. The influence of room acoustics and of the spacing between singers is discussed. The second investigation concerns the effect of spectral variations in the reference sound. Experiments were made primarily with individual singers under laboratory conditions. Changes in vowel quality, and absence/presence of certain partials and of vibrato, were all found to affect somewhat the degree of fundamental frequency agreement between singers. Standard deviation in fundamental frequency between section colleagues in live rehearsal was found to be between 0.10 and 0.15 semitones, or 0.6% and 0.9%. Reference vowels with common partials reinforced by formants were found to increase fundamental frequency precision.