Magnitude-estimation scaling of computerized (digitized) speech under different listening conditions.

The purpose of this study was to evaluate the quality of tape-recorded speech sentences and speech sentences digitized at low, moderate, and high sampling rates by young adults under different listening conditions (quiet vs noise) using magnitude-estimation scaling. A single group of 24 young adults participated as subjects. The tape-recorded speech sentences and digitized speech sentences were presented to each subject in quiet and in the presence of background noise at a signal-to-noise ratio of 0 dB. The subjects were instructed to use magnitude-estimation scaling to evaluate these sentences by assigning a number that corresponded to the speech quality of each sentence. An analysis of variance with repeated measures was performed to assess the effects of mode of speech and listening condition on the magnitude-estimation responses. The analysis showed that the main effects for mode of speech and listening condition were statistically significant. The interactions of mode of speech by listening condition were also statistically significant. Pairwise comparisons showed that the magnitude-estimation responses were higher in the quiet condition than in the corresponding noise condition for each level of mode of speech. Based on the results, the implications of the present study and several avenues for later research are discussed.