Acoustic transitions in Khmer word-initial clusters

Onset clusters in Khmer (Cambodian) often appear with an acoustic transition between consonants, but the phonological status of these elements is indeterminate. If transitions result from gestural separation, they may disappear in fast speech. Acoustic analysis of data from 10 speakers shows that vocalic transitions in Khmer are found in largely predictable set of consonantal contexts. While their presence is modulated by speech rate, they never disappear completely, in some cases becoming more rather than less frequent in fast speech. Clusters contain- ing transitions are generally longer in duration than those that do not, and are also longer than monosyllables containing a lexical schwas, but the transitions do not show any spectral evidence of a distinct gestural target. The possible interpretations of these findings are discussed in the context of the range of articulatory variation known to occur in the implementation of speech rate.