Phonetically governed voicing onset and offset in preschool children who stutter

Abstract

Phonetically governed changes in the fundamental frequency (F₀) of vowels that immediately precede and follow voiceless stop plosives have been found to follow consistent patterns in adults and children as young as four years of age. In the present study, F₀ onset and offset patterns in 14 children who stutter (CWS) and 14 children who do not stutter (CWNS) were investigated to evaluate differences in speech production. Participants produced utterances containing two VCV sequences. F₀ patterns in the last ten vocal cycles in the preceding vowel (voicing offset) and the first ten vocal cycles in the subsequent vowel (voicing onset) were analyzed. A repeated measures ANOVA revealed no group differences between the CWS and CWNS in either voicing onset or offset gestures. Both groups showed patterns of F₀ onset and offset that were consistent with the mature patterns seen in children and adults in previous studies. These findings suggest that in both CWS and CWNS, a mature pattern of voicing onset and offset is present by age 3;6. This study suggests that there is no difference between CWS and CWNS in the coordination of respiratory and laryngeal systems during voicing onset or offset.

Educational objectives: The reader will be able to: (a) discuss the importance of investigating children who stutter close to the onset of stuttering; (b) describe the typical change in F₀ during voicing onset; (c) discuss the potential implications of these results with regard to future research.

Figure 1

Sample waveform depicting /apa/ (V1-C-V2) from the word “papa” Voice offset (V1) and voice onset (V2) vocal cycles determined from negative peak to peak basis are highlighted with circles and shown with tic marks on the x axis.

Figure 2

Average vocal cycle semitone values for F₀ offset and F₀ onset comparing CWS and CWNS. These values are based on both the /apa/ and /itu/ utterances. Values -10 to -1 indicate the last 10 vocal cycles preceding consonant production (offset), and values 1 to 10 indicate the first 10 vocal cycles following consonant production (onset). The black triangles represent the CWS, the open circles represent the CWNS.

Figure 3

Variability (standard deviations) of semitone values for F₀ offset and F₀ onset comparing CWS and CWNS. These values are based on both the /apa/ and /itu/ utterances. Values -10 to -1 indicate the last 10 vocal cycles preceding consonant production (offset), and values 1 to 10 indicate the first 10 vocal cycles following consonant production (onset). The black triangles represent the CWS, the open circles represent the CWNS.

Figure 4

Variability (standard deviations) of semitone values for F₀ offset and F₀ onset comparing CWS and CWNS. These values are based on only the /apa/ utterances. Values -10 to -1 indicate the last 10 vocal cycles preceding consonant production (offset), and values 1 to 10 indicate the first 10 vocal cycles following consonant production (onset). The black triangles represent the CWS, the open circles represent the CWNS.

Figure 5

Variability (standard deviations) of semitone values for F₀ offset and F₀ onset comparing CWS and CWNS. These values are based on only the /itu/ utterances. Values -10 to -1 indicate the last 10 vocal cycles preceding consonant production (offset), and values 1 to 10 indicate the first 10 vocal cycles following consonant production (onset). The black triangles represent the CWS, the open circles represent the CWNS.