Understanding VOT variation in spontaneous speech

This paper reports a corpus study on the variation of VOT in voiceless stops in spontaneous speech. Two speakers’ data from the Buckeye corpus are used: one is an older female speaker with a low speaking rate while the other is a younger male speaker with an extremely high speaking rate. Linear regression analysis shows that place of articulation, word frequency, phonetic context, speech rate and utterance position all have an effect on the length of VOT. However, altogether less than 20% of the variation is explained in both speakers, which suggests that pronunciation variation in spontaneous speech is a highly complicated phenomenon which might need more sophisticated modeling. Our results also show a great deal of individual differences.