Resonance Tuning in Professional Operatic Sopranos

Soprano singers are capable of singing at pitches exceeding 1000 Hz, where the spacing of the harmonics means that the vocal tract resonances are not fully utilised. Sopranos therefore move the articulators, to "tune" the resonances of the vocal tract near to harmonics of the voice source, improving the efficiency of sound production. Although resonance tuning has been observed in soprano singers, it is not yet understood how this phenomenon is achieved and which articulators play the most significant roles in altering the vocal tract resonances.
A preliminary experiment explored the use of broad band noise excitation of the vocal tract to observe resonance tuning behaviour in girl choristers. A second experiment extended this procedure to include MRI to observe the vocal tracts of 6 professional soprano opera singers and investigate how the articulators affect vocal tract resonances. The effects of MRI measurement conditions on singers were also investigated to establish whether measurements obtained during MRI are representative of normal singing. Finally, a perceptual test was conducted to study the perception of different methods of resonance tuning.
As expected, considerable R1:f0 tuning, and some R2:2f0 tuning was observed in both groups. MRI revealed some links between resonances and articulators, however no consistent patterns in production were observed across subjects. The results showed strong differences in resonance production between different vowels and subjects, suggesting that resonance tuning production is not only a complex and context-specific topic, but also highly individual.