The Evaluation of Vocal Pitch Accuracy

The objective analysis of Western operatic singing voices indicates that professional singers can be particularly “out of tune.” This study aims to better understand the evaluation of operatic voices, which have particularly complex acoustical signals. Twenty-two music experts were asked to evaluate the vocal pitch accuracy of 14 sung performances with a pairwise comparison paradigm, in a test and a retest. In addition to the objective measurement of pitch accuracy (pitch interval deviation), several performance parameters (average tempo, fundamental frequency of the starting note) and quality parameters (energy distribution, vibrato rate and extent) were observed and compared to the judges’ perceptual rating. The results show high intra and interjudge reliability when rating the pitch accuracy of operatic singing voices. Surprisingly, all the parameters were significantly related to the ratings and explain 78.8% of the variability of the judges’ rating. The pitch accuracy evaluation of operatic voices is thus not based exclusively on the precision of performed music intervals but on a complex combination of performance and quality parameters.