Geringer, J. M., MacLeod, R. B., & Sasanfar, J. K. (2015). In Tune or Out of Tune: Are Different Instruments and Voice Heard Differently?. Journal Of Research In Music Education, 63(1), 89-101. doi:10.1177/0022429415572025

Main point: diff. instruments are perceived differently to be or not to be in tune with piano acc. Soprano vocalist was heard as more in tune than the violonist and trumpeter. Particulary if the deviation was toward sharp direction.

My first concern when reading this abstract – what temperation did they use for Bach? Answer comes later in text – equal 440Hz. Well, OK, it’s in C major.

Interesting citation: Lindgren, Sundberg (1979) found that experienced listeners accepted errors of 50-70 cents as in tune. Easier to accept are sharp notes, emotionally prominent points, metrically unstressed situations, real audio not synth.

Curious fact: they had hard time finding a soprano who would sing in tune

Procedure: they recorded players, then used AutoTune to manipulate the tunings.

Cites Estonians! Vurma, Ross, Kuuda.

Takeaway: when designing automatic feedback for vocalist, be prepared for lots of out-of-tune performances that people claim to be in tune. Need more tolerance for vocal as compared to other instruments.