Clear speech sounds fast: The impact of speaking mode variation on perceived tempo

Research has identified multiple acoustic cues for perceived speech tempo variation. Together, these warrant the proposal that speech which conveys more complex spectral information is heard as taking more time than speech conveying less complex information; if timing is controlled, the former sounds faster than the latter. We therefore hypothesize that hyper-articulated speech sounds faster than normal speech when articulation rates are controlled. We report on two listening experiments which address this hypothesis using clear and normal sentence productions. Experiment 1 assesses listeners’ ability to separate tempo and speaking mode judgements; Experiment 2 uses the same stimuli to probe the direction of any effect of speaking mode variation on perceived tempo. The results confirm that compressed clear sentence productions sound faster than normal productions with the same duration, although the precise mechanism underlying this effect remains to be established.