The present study investigates the effect of controlling speech rate on listening comprehension of Iranian students majoring in English. It was somehow the application of Krashen's 'input hypothesis'(1985). There were two homogeneous groups each comprising 40 students taking 'Oral Translation 3'. In the experimental group there were 28 females and 12 males, in the control group there were 30 females and 10 males. The age of the subjects ranged from 22-28.The selected material was authentic American English spoken by fluent native speakers in the programs such as 'Opera' and 'Dr. Phill'. The students were worked with in a well equipped language laboratory. The experimental group had the advantage of modified speech through Ulead software version 11. The control group just enjoyed the possibility of a five time repetition for each individual sentence. At the end two reliable and valid M.C. listening comprehension and cloze tests were prepared from the covered materials and administered to them. The cloze test was based on the exact word version (Chaudron, 1986). Based on the results of this study it was concluded that there were no significant differences between the mean scores of the experimental and control groups on the multiple choice and cloze tests at .05 level of significance. This implies that first, the experimental group did not do any better than the control group and second, the students were not able to apply the benefits of slowing down the speech to authentic texts and for speeches delivered at a normal rate.
