When S hears his own voice with a small time delay his speech may be seriously affected. The effects produced by delayed auditory feedback (DAF) include prolongation of vowels, repetition of consonants, increased intensity of utterance, and other articulatory changes. The significance of individual differences in susceptibility to DAF is considered in relation to personality and physiological characteristics. The technique may prove useful in the detection of auditory malingering and has possible implications for the understanding of stammering. The discussion relates the findings to models of speech control. Methodological problems and future research needs are outlined. (74 ref.)