A listening experiment was carried out to test the hypothesis that four phonologically less complex intonation contours are perceived as faster than four related more complex contours. In the main, the hypothesis is confirmed. In the case of one of the four less complex contours, the increase in perceived speech rate was considerably greater than in the case of the other three. A follow-up experiment showed that this greater effect is to be attributed to the particular shape of the contour (the “flat hat” contour of ’t Hart & Collier, 1975), which contains a high, fairly monotonous contour section. There are indications that the general explanation for the difference in perceived speech rate between the two sets of contours is to be found in the implied presence of an “intonational phrase” boundary in the contours that were perceived as slower, rather than in the greater complexity of the contours.