I am pondering whether or not the vibrato traditionally present in Western classical singing (Bel Canto) bears any significant influence on perturbation or noise measures – vibrato has been defined as variance in frequency and amplitude, as well as having aerodynamic interaction with vocal-fold vibration/oscillation. I am unsure if clinical measures such as VTI, HNR, RAP, etc will be confounded by its presence in sung voice samples. The majority of literature I've looked at supports CPP(S) as one of the most robust acoustic voice measurements across a wide variety of tasks, but I am wanting to include other measures in my analysis of singing students too. Any insight or ideas? Thank you.