Toward a cognitive framework of expert singing-voice evaluation in bel canto pedagogy: a longitudinal exploratory...

Classical singing pedagogy relies on expert judgments that integrate auditory-perceptual cues, embodied pedagogical knowledge, and specialized evaluative language. This exploratory, longitudinal study proposes a cognitive framework, centered on Polanyi's concept of tacit knowledge, for describing how experienced bel canto pedagogues perceive singing-voice development from a brief excerpt. Twenty female soprano students (7 music-education, 13 vocal-performance majors) sang the word 'tanto' from Caro mio ben at university entry (Z1) and after 2 years of instruction (Z2). Four professional singers and voice pedagogues, blind to institutional affiliation, rated perceived development on a 0-2 scale and selected evaluative terms from a 27-item Italian pedagogical vocabulary; median ratings, rather than the mean of an even number of raters, served as the primary outcome. Acoustic analysis proceeded in two exploratory, descriptive stages. First, the singer's-formant ratio (SFR) and a Q-value index were compared with a pedagogical reference recording (M2025) using path-length-normalized dynamic time warping. Movement toward M2025 did not correspond consistently with expert ratings: several students whose SFR/Q-value profiles moved toward M2025 received low or zero median ratings (e.g., E06, E07, V07), whereas six students whose profiles moved away from M2025 on both indices received high median ratings of 1.5-2 (E02, E05, V01, V02, V03, V06). Second, changes in alpha ratio, H1-H2, spectral centroid, smoothed cepstral peak prominence (CPPS), and singing power ratio (SPR) were examined descriptively alongside participants' evaluative terms, without regression or machine-learning modeling, given the small, non-random sample. Case-level analysis indicates that experts attended to qualitatively different cues depending on what they heard in a given voice-e.g., basic, mouth-opening- and resonance-related terms (S07, R02) versus depth- and vibrato-related terms (R10, S09)-independent of institutional cohort. We propose a Polanyi-centered interpretive framework in which candidate acoustic correlates, the 27 evaluative terms (understood, after Vygotsky, as mediating cultural-linguistic tools), and Dreyfus-and-Dreyfus-informed developmental sensitivity jointly, but only partially, illuminate the focal judgment that pedagogically meaningful development has occurred. The framework is hypothesis-generating rather than confirmatory; no predictive or inferential claims are made about the acoustic determinants of expert judgment.