INTRODUCTION: Electrophysiological evidence has reinforced the hypothesis that stuttering is associated with a deficit in modulation of the cortical auditory system during speech planning, contributing to an inefficient auditory feedback monitoring and, consequently, resulting in disfluencies. OBJECTIVE: To verify the impact of auditory feedback modifications on the spontaneous speech of individuals with stuttering. METHODS: Sixteen individuals, of both genders, aged 8-17 years and 11 months, with a diagnosis of persistent neurodevelopmental stuttering, were divided into two groups: Moderate Stuttering Group and Severe Stuttering Group. The testing procedures consisted of three stages: collection of identification data, audiological assessment and fluency evaluation of spontaneous speech in four auditory feedback conditions (non-altered, delayed, masked and amplified). The speech sample obtained in the non-altered feedback was considered the control; the others were considered as modified listening conditions. RESULTS: Regarding the stuttering-like disfluencies, a statistically significant difference was observed in the intragroup analysis of the Moderate Stuttering Group between non-altered and masked auditory feedback (p = 0.042), as well as between non-altered and amplified (p = 0.042). There was a statistically significant difference in the Severe Stuttering Group for all auditory feedback modifications in relation to the non-altered (delayed p = 0.012, masked p = 0.025 and amplified p = 0.042). There was also a reduction in flows of syllables and words-per-minute in the Moderate Stuttering Group for the delayed auditory feedback, as compared to non-altered (p = 0.017 and p = 0.025, respectively). CONCLUSION: The effect of delayed auditory feedback was favorable for the Severe Stuttering Group, promoting speech fluency. The conditions of masked and amplified auditory feedback resulted in speech benefits in both groups, decreasing the number of stuttering-like disfluencies. The speech rate was not impaired by any listening condition analyzed.