Comparison of period-by-period fundamental frequency of stutterers and nonstutterers over repeated utterances.

The fundamental frequency (f phi) of the first five periods in the acoustic wave form of vowels following stop consonant productions and the f phi of a period approximately 100 ms into the vowel were analyzed in the repeated fluent utterances of 10 nonstutterers and 10 stutterers both pre- and posttherapy. Group data indicate that the nonstutterers and stutterers showed similar f phi diminution patterns in vowels immediately following stop consonants. Additionally, the stutterers were not significantly different from the nonstutterers in their ability to achieve a stable f phi over repeated utterances. These results are discussed with respect to a previous analysis of the present data (Sacco & Metz, 1986) in which it was found that stutterers were significantly more variable than nonstutterers in their ability to achieve a stable f phi over repeated utterances. It is suggested that stutterings in the immediate vicinity of otherwise fluently produced words may influence certain production characteristics of those words.