A comparative study of the effect of two time-alteration techniques on listener comprehension

The purpose of this investigation was to determine if listener comprehension is differentially affected by two different techniques of time alteration: the sampling method and the harmonic compression method. The Nelson-Denny Reading Test, consisting of 8 selections of scientific and literary content appropriate for college students with respect to interest and level of difficulty, was presented to 3 groups of 40 Ss each; each group was given the tape-recorded test after processing at one of the 3 speech rates, normal, half normal, or twice normal rate. Of the 8 selections on this test, 4 were processed by sampling using a VARISPEECH-I compressor/expander, and 4 were processed by harmonic compression using a Lockheed LM-312 Pitch Normalizer. There were of course some differences in listener comprehension as a function of rate, but within each of the rate conditions there were no significant differences as a function of method of time alteration. With the type of speech material used here, and within these rate conditions, these time alteration methods can be used interchangeably in such research.