Table 1.

High-speed video (HSV)-derived parameters estimated from the glottal area waveform and their physiologic interpretation.

HSV Parameter	Physiologic / Voice Source Interpretation
Mechanical Parameters
Maximum Area Declination Rate, normalized (MADRn)	Normalized measure of closing velocity and closure abruptness, related to glottal excitation characteristics
Amplitude-to-Length Ratio (ALR)	Magnitude of vocal fold vibratory excursion normalized to glottal length, reflecting the degree of glottal opening and vibratory amplitude
Closing Quotient (ClQ)	Relative duration of the closing phase of the glottal cycle, reflecting closure dynamics and abruptness of glottal closure
Speed Index (SI)	Relative timing balance between opening and closing phases of the glottal cycle, related to temporal skewing of the waveform and conceptually related to speed quotient
Stiffness Index (STI)	Rate of glottal area change normalized to vibratory amplitude, reflecting vibratory stiffness and rapidity of glottal excitation
Symmetry and Periodicity Parameters
Phase Asymmetry Index (PAI)	Left-right symmetry of vibratory phase
Time Periodicity (TP)	Cycle-to-cycle duration stability and vibratory periodicity
Waveform Symmetry Index (WSI)	Left-right symmetry of the shape and timing of the glottal area waveform