Variable speech control vs Varispeech: does newer mean better?

Abstract

Normal-hearing volunteers (N:30, aged 19-28 yrs) yielded intelligibility scores for W-22 word lists and CID sentences at 40 db re each S's SRT, and judgments on a 7-pt scale ("very pleasant"----"very unpleasant") for Sentence 3 of Fairbanks' "Rainbow Passage". Normal and time-altered speeds (60%: compression; 140%: expansion) were compared between the widely-used but obsolescent Lexicon Varispeech (VSp) unit vs the commercially available Variable Speech Control Model A-7 which incorporates a time-sampling technique similar to the VSp. With both VSp and VSC, intelligibility was nearly perfect at all three speeds, and thus both appear equally suitable for intelligibility studies, but at the 60% and 140% speeds the signal clarity was significantly preferable for the VSp system (p less than .01 in both cases), by .6 of a scale interval at 60% and 1.8 interval at 140%. Furthermore, the VSC does not operate beyond the 60-140% range, as occasionally may be desirable in research on the effects of time alteration on speech reception.