On pitch jumps between chest and falsetto registers in voice: Data from living and excised human larynges

The paper offers a new concept of studying abrupt chest-falsetto register t ransitions Clumps) based on the theory of nonlinear dynamics. The jumps wer e studied in an excised human larynx and in three living subjects tone fema le and two male). Data from the excised larynx revealed that a small and gr adual change in tension of the vocal folds can cause an abrupt change of re gister and pitch. This gives evidence that the register jumps are manifesta tions of bifurcations in the vocal-fold vibratory mechanism: A hysteresis w as observed; the upward register jump occurred at higher pitches and tensio ns than the downward jump. Due to the hysteresis, the chest and falsetto re gisters can be produced with practically identical laryngeal adjustments wi thin a certain range of longitudinal tensions. The magnitude of the frequen cy jump was measured as the "leap ratio" F-0F:F-0C (fundamental frequency o f. the falsetto related to that of the chest register) and alternatively ex pressed as a corresponding musical interval, termed the ''leap interval." R anges of this leap interval were found to be different for the three living subjects (0-5 semitones for the female, 5-10 and 10-17 for the two males, respectively). These differences are considered to reflect different biomec hanical properties of the, vocal folds of the examined subjects. A small ma gnitude of the leap interval was associated with a smooth chest-falsetto tr ansition in the female subject. (C) 1999 Acoustical Society of America. [S0 001-4966(99)06308-0].