Singing together: Pitch accuracy and interaction in unaccompanied unison and duet singing

This paper investigates singing interaction by analysis of the factors influencing pitch accuracy of unaccompanied pairs of singers. Eight pairs of singers sang two excerpts either in unison or two-part harmony. The experimental condition varied which singers could hear singing partners. After semi-automatic pitch-tracking and manual checking, this paper calculated the pitch error (PE) and interval error and tested the factors of influence using a one-way analysis of variance and a linear mixed-effects model. The results indicate that: (1) singing with the same vocal part is more accurate than singing with a different vocal part; (2) singing solo has less pPE than singing with a partner; (3) PEs are correlated, as singers adjust pitch to mitigate a partner's error and preserve harmonic intervals at the expense of melodic intervals and absolute pitch; (4) other factors influence the pitch accuracy, including: score pitch, score harmonic interval, score melodic interval, musical background, vocal part, and individual differences.