Phase Difference Of Oscillations Research Articles

Phase differences in RHEED oscillations of various beams during epitaxial growth of GaAs(100) by MBE

Phase differences in RHEED oscillations of various beams during epitaxial growth of GaAs(100) by MBE

Two‐mass model of the larynx: Vocal fold vibration as a negative differential resistance oscillation

The vocal folds were analyzed as a two‐mass model assuming zero glottal resistance and no supraglottal pressure recovery. Steady longitudinal flow calculations similar to those of Ishizaka and Matsudaira [SCRL Monograph No. 8 (1972)] were made, but assuming subglottal pressure varied through a sequence of steady states. A negative differential resistance was found when the dc displacement of the upper mass was small compared to that of the lower mass. Dynamic motion of the masses was represented by a pair of series resonant circuits within the glottis and transverse to the steady flow. The transverse circuits are isolated from the trachea and vocal tract by the resistances at the entrance and exit of the glottis. Sustained, self‐excited, small‐amplitude oscillations can be obtained when the magnitude of the negative differential resistance was equal to the real part of the circuit impedance. The oscillation frequency and phase difference between the masses depended only on myoelastic properties of the larynx. By contrast, oscillation frequency and phase in Ishizaka and Matsudaira's analysis also depends on dc aerodynamics. The calculations are therefore not contained in Ishizaka and Matsudaira's analysis. The difference in predictions should be resolved by experiment on linear controllable mechanical models.