The intelligibility of Dutch sentences in which specific vowels were systematically replaced by the Dutch vowel /oe/ was tested. The prosodic features of the vowels were copied to their substitute by using the TD-PSOLA technique. Plausibility of the sentences appeared to be the predominant factor in this experiment. Word frequency had only a small effect. For function words the number of correct responses was higher than for content words. A word stress effect could not be demonstrated.