A BRIEF review of the research on delayed auditory feedback would appear tv be appropriate before proceeding to describe its utility in stuttering therapy. As now we know well, when a speaker's speech is'returned to his ears a fraction of a second after the time it normally would arrive, certain changes in his speech occur. His verbal output tends to be slowed down (Black, 1951); repetitions of syllables and prolongations of sounds are observed (Lee, 1951); the speech becomes slurred and certain sounds are distorted or omitted (Ham and Steer, 1967). The artificial stutter and the articulation errors were viewed by Fairbanks and Gunman (1958) as the primary behaviours produced by the delay. However, according to these authors, the other behaviors such as an increase in the pitch of the voice and an increase in vocal intensity together with pauses, palmar sweating and flushing were seen as reactions to the experience.It should be mentioned that there exists a wide individual variability in all these reactions, whether primary or secondary (Beaumont and FOSS, 1957). Some individuals indeed seem to be relatively unaffected by DAF : other persons show a proclivity toward repetitions while others prolong their vowels. Some react with marked pitch changes or increases in loudness; a few even demonstrate difficulty in word finding (Meyer-Epler and Luchsinger, 1965). Males seem more vulnerable than females (Bachrach, 1964). Chase and his co-workers (1961) reported that older children and adults are more affected than the younger ones but other recent research by MacKay (1968) does not substantiate this. Adaptation to DAF can be achieved, despite some of the earlier research (Atkinson, 1953 and Neelley, 1956)~ but usually only after prolonged exposure (Goldiamond, 1965;Winchester, Gibbons and Krebs, 1959). Some lingering effects in terms of disrupted speech has been reported by Black (1955) and others but these seem to be transient.The question has been posed as to whether or not the repetitions and prolongations shown under DAF are similar or identical with stuttering behaviors. Neelley's (1961) research seemed to indicate that they were not; however, Yates (1963) and others have criticized the design of his study and especially his conclusions.A rather surprising finding is that certain stutterers (Soderberg, 1969)~ especially the more severe ones, speak much better under DAF than under normal feedback conditions. Chase (1958) reported that children who showed more repetitions in their speech than normal improved in fluency under DAF. Nessel (1958) in Germany found that some stutterers spoke better under DAF; so also did Lotzman (1961) who studied 60 stutterers and used a variety of delay times. Adamzcyk (1963) in Poland, Bohr (1963) in South Africa, Zerneri (1965 in Italy, and a number of workers in the United States have demonstrated that certain stutterers speak much more fluently under DAF. A very interesting study was done by Cohen and Richards (1965). They attempted to interfere with the stutterer's presumed...