THE EFFECTS OF FLUENCY-EVOKING CONDITIONS ON VOICING ONSET TYPES IN PERSONS WHO DO AND DO NOT STUTTER

Voicing onset changes between control conditions and three fluency-evo king conditions (choral reading [CHORAL], delayed auditory feedback [D AF], and noise [NOISE]) were studied in 12 persons who do not stutter and 10 who do stutter. Voicing onsets were distinguished physiological ly using airflow prior to voicing, with zero airflow prevoicing catego rized as hard and the rest as breathy. Persons who stutter were more f luent under all fluency-evoking conditions than control conditions. Sp eaking under fluency-evoking conditions did not significantly increase the overall proportion of breathy onsets from control conditions for either group. However, looking only at hard onsets in the control cond ition, we found that both groups changed significantly more to breathy (p = 0.001) under CHORAL and NOISE. In persons who stutter, onset typ e was not associated with whether a word was produced fluently or dysf luently in the control condition. Also, no relationship was found betw een onsets changing to breathy under fluency-evoking conditions and on sets changing to fluent. The results suggest that although fluency-evo king conditions can modify some voicing onset behaviors, these modific ations do not relate to improvements in fluency. Published by Elsevier Science Inc.