Objective: Jazz vocalists utilize an expansive range of timbres in their expression of a song. Despite its uniquely rich color palette, jazz-style singing remains markedly underrepresented in voice research. This study investigates the use of timbres employed by jazz vocalists while singing expressively by examining the spectrum centroid of spectral moments within the performance of a jazz standard ballad. The aim of this study is to determine to what degree timbre plays a role in vocal expression in jazz-style singing and the commonalities and differences between each jazz vocalist’s use of timbre.

Methods: Three female fourth-year undergraduate jazz vocal performance students were asked to sing the jazz standard “Misty” in the key of C Major. Four samples were collected from each subject: two sung with expression and two sung with no affect. Each sample was recorded using an Earthworks M23 microphone into Praat software. Samples were then annotated using Praat software to extract all syllables sung on pitches G4 (392 Hz) and A3 (220 Hz). Each of these data points were analyzed for spectrum centroid.

Results: Preliminary results show that the expressive sample sets yielded a wider range of spectrum centroid, and thus had more timbral variability, compared to the sample sets with no affect. Additionally, results highlight the similarities and differences between each subject’s timbral choices in their interpretation of the song.

Conclusions: This study represents one of the first comparisons of different jazz vocalists and their use of timbre. The results reveal that timbral variability is a tool jazz vocalists use in expression, but its application varies based on each vocalist’s individual interpretation of a song.