Maximum duration of sustained [s] and [z] and the s/z ratio with controlled intensity

The purpose of this study was to compare maximum prolongations of controlled-intensity /s/ vs. /z/ in young healthy male and female adults and to compare the s/z ratio in young men and women. Twenty young adult men and 20 young adult women were included in this study. Participants produced 10 trials of /s/ and 10 of /z/ with a controlled intensity of 60-dB sound-pressure level (SPL). Maximum prolongations and s/z ratio were determined by three different methods: based on the longest out of 10 trials, the longest of 3 trials, and an average of the first 3 trials. Results revealed that based on averaged group data, /s/ and /z/ seemed to be prolonged for similar durations. Men consistently prolonged both phonemes significantly longer than women. There were no significant differences in s/z ratio between men and women. However, when individual data were reviewed, it seemed that some subjects consistently prolonged /s/ for a longer duration than /z/, some subjects prolonged /z/ longer than /s/, and some subjects actually produced approximately equal durations of the two phonemes. It was further noted that /s/ durations were more favorably impacted by practice than /z/ durations.