An Empirical Approach to Studying Intonation Tendencies in Polyphonic Vocal Performances

Background in music theory and analysis. Polyphonic vocal intonation practices have been addressed in a number of studies on vocal acoustics. Our research both builds on this work and supplements it with a theoretical paradigm based on work done in the areas of sensory consonance and tonal attraction. Background in computing. Recent work in the field of music information retrieval has discussed the main obstacles related to tracking pitches in a polyphonic signal and has provided some techniques for working around these problems. Our method for analyzing the pitch content of recorded performances draws extensively on this work and on the knowledge made available to us by the musical scores of the pieces being performed. Aims. Our research is focused on the study and modeling of polyphonic vocal intonation practices through the intersection of computational and theoretical approaches. We present a methodology that allows for a detailed model of this aspect of polyphonic vocal performance practice to be built from analyses of numerous recordings of real-world performances, while working within a robust theoretical paradigm. Main contribution. In the computational component of the research a number of a cappella polyphonic vocal recordings are analyzed with signal processing techniques to estimate the perceived fundamental frequencies for the sung notes. These observations can be related to the musical context of the score through machine learning techniques to determine likely intonation tendencies for regularly occurring musical patterns. A major issue in developing a theory of intonation practices is the potential conflict between the vertical and horizontal intonational impetuses. To assess this conflict in greater detail we have constructed a theoretical approach where theories of sensory consonance account for vertical tuning tendencies and theories of tonal attraction account for the horizontal tendencies. Implications. In the field of music cognition, our research relates to work being done in the area of musical expression. If the intonation tendencies inferred from the end results of this research are taken as a norm, then deviations from this norm, when these deviations are musically appropriate, can be viewed as expressive phenomena. Computer software implementing such results will allow composers and musicologists to hear more intonationally accurate digital re-creations and may also function as a training guide for vocalists.