Purpose: The effect of frequency altered feedback (FAF) on stuttering type (i.e., prolongation, repetition, or silent block) and stuttering duration (i.e., average duration of stuttering event and total stuttering time) was examined. Method: Retrospective analyses of previously collected data from 12 adult persons who stutter who participated in an "ABA" time-series design while reading orally was undertaken. It was hypothesized that stuttering duration would decrease and there would be a differential reduction in the type of stuttering during FAF, concurrent with previously confirmed reduction of stuttering episodes. A total of 2,971 stuttered syllables were analyzed. Results: The total stuttering duration (s/min) was significantly reduced by approximately 50% irrespective of stuttering type (p = 0.0014). Although significant differences in the average duration(s) of the 3 stuttering types (p = 0.0064) existed, FAF significantly reduced each type of stuttering by approximately 20% (p = 0.0055). There was no differential effect on the reduction of proportion of stuttering type during FAF (p = 0.36). Conclusions: FAF positively affects the speech of persons who stutter by reducing the proportion of stuttered events with a concomitant decrease in duration of residual stuttering and total stuttering time during oral reading.