Perceptual normalization for speaking rate: effects of temporal distance.

A series of studies was undertaken to examine how rate normalization in speech perception would be influenced by the similarity, duration, and phonotactics of phonemes that were adjacent or distal from the initial, target phoneme. The duration of the adjacent (following) phoneme always had an effect on perception of the initial target. Neither phonotactics nor acoustic similarity seemed to have any influence on this rate normalization effect. However, effects of the duration of the nonadjacent (distal) phoneme were only found when that phoneme was temporally close to the target. These results suggest that there is a temporal window over which rate normalization occurs. In most cases, only the adjacent phoneme or adjacent two phonemes will fall within this window and thus influence perception of a phoneme distinction.