The inhibitory effects of continuously presented audio signals (/a/, /s/, 1,000 Hz pure-tone) on stuttering were examined. Eleven adults who stutter participated. Participants read four 300-syllable passages (i.e. in the presence and absence of the audio signals). All of the audio signals induced a significant reduction in stuttering frequency relative to the control condition (P = 0.005). A significantly greater reduction in stuttering occurred in the /a/ condition (P < 0.05), while there was no significant difference between the /s/ and 1,000 Hz pure-tone conditions (P > 0.05). These findings are consistent with the notion that the percept of a second signal as speech or non-speech can respectively augment or attenuate the potency for reducing stuttering frequency.