The "Overdrive" Mode in the "Complete Vocal Technique": A Preliminary Study.

"Complete Vocal Technique," or CVT, is an internationally widespread method for teaching voice. It classifies voicing into four types, referred to as "vocal modes," one of which is called "Overdrive." The physiological correlates of these types are unclear. This study presents an attempt to analyze its voice source and formant frequency characteristics. A male and a female expert of CVT sang a set of "Overdrive" and falsetto tones on the syllable /pᴂ/. The voice source could be analyzed by inverse filtering in the case of the male subject. Results showed that subglottal pressure, measured as the oral pressure during /p/ occlusion, was low in falsetto and high in "Overdrive", and it was strongly correlated with each of the voice source parameters. These correlations could be described in terms of equations. The deviations from these equations of the different voice source parameters for the various voice samples suggested that "Overdrive" phonation was produced with stronger vocal fold adduction than the falsetto tones. Further, the subject was also found to tune the first formant to the second partial in "Overdrive" tones. The results support the conclusion that the method used, to compensate for the influence of subglottal pressure on the voice source, seems promising to use for analyses of other CVT vocal modes and also for other types of phonation.