The Effects of Stress Type, Vowel Identity, Baseline f 0 , and Loudness on the Relative Fundamental Frequency of Individuals With Healthy Voices

Relative fundamental frequency (RFF) has been investigated as a possible acoustic measure to assess laryngeal tension. This study aimed to identify possible factors in RFF stimuli (stress type, vowel identity, baseline f , and loudness) that might also affect RFF values. Fifteen speakers with healthy voices produced short RFF stimuli (vowel-/f/-vowel; eg, /ɑfɑ/) in different conditions. They produced the stimuli with three different stress types and four different vowels. Participants also produced stimuli in three different baseline f conditions and three different loudness conditions. The mean RFF and within- and between-subject standard deviation (SD) of RFF were estimated for each stimuli condition. Stress type had a statistically significant effect on RFF means and within-subject SDs with a large effect size (P