Word Intelligibility in Multi-voice Singing: The Influence of Chorus Size.

Objective: This study investigated how the intelligibility of sung words is influenced by the number of singers in a choral music style.

Methods: The study used repeated measures factorial. One hundred forty-nine participants listened to recordings of spoken and sung English words and attempted to identify the words. Each stimuli word was sung or spoken in sync by either one, four, eight, sixteen, or twenty-seven members of a high-quality Soprano Alto Tenor Bass (SATB) choir.

Results: In general, single-voice word recognition was higher than multi-voice word recognition in the sung condition. However, the difference between four concurrent singers and the full choir was negligible; that is, reduced intelligibility with multiple singers shows little sensitivity to the number of singers. The principal effect of voice density on intelligibility is found to occur with coda consonants-a result consistent with the importance many choral conductors attribute to coordinating word offsets. In particular, the plosives /b/, /d/, /g/, and /p/ are easily confused. Coda liquids (/l/,/r/) were also found to be a source of confusion. Finally, an increasing density of voices appears to have a facilitating effect for the coda nasal /m/.

Conclusions: Groups of four or more choral singers do appear to be less intelligible than single singers, although the observed effect is modest. However, increasing the number of singers in a choral texture beyond four singers does not appear to further degrade intelligibility.