Characterizing and improving vibrato in the singing voice
Noam Amir; Ofer Amir; Irit Ronen

Vibrato is widely used by singers and instrument players to embellish their performance, most often in sustained notes. In this paper we describe our ongoing research on various aspects of this subject. Our initial attempts to characterize vibrato stemmed from a search after quantitative measures for vibrato quality, in order to compare vibrato before and after vocal warmup. A set of measures in time and frequency domain was defined, and used to evaluate the vibrato quality of a group of singing students. These objective measures were later correlated with subjective evaluations by singing teachers, and combined through an optimization process by linear weighting to obtain a single figure representing vibrato quality. This was implemented in a real-time “vibratometer” giving the singer visual feedback on their vibrato. Our further research examines vibrato characteristics of several singing styles – classical, jazz and pop. Sustained notes sung by well known singers in commercial recordings are analyzed. At this stage we present the methodology used to distinguish the singer’s vibrato from the multitude of accompanying instruments, and various parametric methods for quantifying the vibrato contour.