Revisiting Sustained Phonation Time of /s/, /z/, and /α/

Research studies of maximum phonation time, have questioned its validity and value as a tool to assess laryngeal competence. This study proposes a fresh look at phonation time, from a different perspective. The interrelationships of the durations between semiocclusion vs. open vocal tract (/s/-/z/ vs. /α/) and voiced vs voiceless (/z/-/α/ vs. /s/) sound are examined to determine whether this approach might provide additional clinical insight into the respiratory phonatory efficiency of patients.

Comfortable sustained phonation time of /s/, /z/ and /α/ was collected as part of the voice evaluation of patients referred by laryngologists for voice therapy. Inclusionary criteria: male and female subjects 19 years of age or older. Exclusionary criteria: autoimmune disorders, malignancies, major pulmonary/respiratory disorders.

A total of 218 patients (150 females and 68 males) mean age of 53.6 met all the criteria. Means, standard deviations and t test were conducted to determine whether significant differences existed. t test results indicate significance between s/z P = 0.002 and z/α P = 0.004 for females but only slight significance in s/α P = 0.03 for males. Close analysis of individual results observed four (4) different conditions or effects of fricative/semiocclusion and voicing: the close durations of the /s/ and /z/ relative to the /α/; the /z/ and /α/ are close in duration relative to the /s/; the spread of more than 5 seconds between /s/, /z/ and /α/ relative to the others; and similar duration of /s/, /z/, and /α/.

Significant differences exist in the durations of comfortable phonation time of sustained /s/ and /z/ and /α/ thought to be related to effects of semiocclusion, fricative consonants, and voicing. Phonation time should be seen not only in terms of duration, but the interplay of the phonemic qualities of the sounds as they relate of laryngeal efficiency.