Copyright © American Speech-Language-Hearing Association From: Phonatory Air Flow Characteristics of Adductor Spasmodic Dysphonia and Muscle Tension Dysphonia J Speech Lang Hear Res. 1999;42(1):101-111. doi:10.1044/jslhr.4201.101 Legend: Measurement of mean phonatory air flow and air flow perturbations. Air flow landmarks used to select the interval from which mean phonatory air flow was measured are shown, and this interval is labeled as A. Coefficients of variation were computed from all of the air flow values within this segment of the waveform. One air flow perturbation is shown in the first syllable for SD2. It is marked with an asterisk (*). Other fluctuations in air flow magnitude for SD2 were not large enough to meet our amplitude criterion for air flow perturbations. The troughs used to measure the duration of the air flow perturbation are marked, and this interval is labeled as B. Date of download: 10/19/2017 Copyright © American Speech-Language-Hearing Association