This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Expert listeners can often form an immediate impression of a singer's performance. But what exactly in the voice drives that judgment?
In classical vocal competitions, performers are rated on an overall score. However, the criteria behind that score are rarely made explicit. Moreover, voice quality is often described in vague, metaphorical terms, such as "ringing," "warm" or "focused," which can mean different things to different listeners.
To better understand what lies behind these judgments, a team of researchers led by assistant professor Haruka Kondo from the Graduate School of Media and Governance, Keio University, Japan, along with Dr. Sotaro Kondoh from the Faculty of Environment and Information Studies, Keio University, and Japan Society for the Promotion of Science, Japan, and associate professor Shinya Fujii from the Faculty of Environment and Information Studies, Keio University, Japan, simulated a vocal competition in a concert hall, asking expert judges to evaluate the singers and investigating which vocal attributes and acoustic features were associated with higher overall scores. The study, to be published online in the Journal of Voice on Oct. 27, 2026, provides measurable ways to understand how experts evaluate classical singers.
Assistant professor Kondo is a Ph.D. student in vocal science at Keio University and an operatic soprano who has competed in various vocal competitions. She conducted the study with Kondoh, Ph.D., a Japan Society for the Promotion of Science research fellow and visiting research fellow in musical meter, beat and rhythm perception, and associate professor Fujii, Ph.D., who specializes in the neuroscience of music and directs Keio University's Neurosciences and Music Laboratory. The researchers are affiliated with Keio University's Research Center for Music Science, which uses scientific approaches to study how music is perceived, understood, created and experienced, as well as its effects on the brain, mind and body.
"Our study bridges the gap between artistic intuition and science and does not aim to replace the expert ear. It helps translate what experienced listeners hear into a shared, measurable language," says Kondo. The researchers recruited 22 classical singers, including 10 men and 12 women.
Each singer performed the same song, "Caro mio ben," a cappella, without instrumental accompaniment, in a concert hall to recreate the conditions of a live performance. Five expert judges gave each performance an overall score on a 100-point scale and rated six vocal attributes on a seven-point scale, covering aspects such as pitch variation (vibrato), voice quality (resonance and timbre), clarity of words (diction), pitch accuracy (intonation) and expressiveness. The participants' voices were also analyzed for four acoustic features: singing power ratio, which reflects the prominence of certain frequencies in the voice; loudness units relative to full scale, a standardized measure related to perceived loudness; vibrato rate, which describes how quickly the pitch changes during vibrato; and vibrato extent, which describes the amount of pitch change during vibrato.
Extract — continue reading at the source.
