The impact of relative average duration of vowels in greek on the perception of a constant synthetic speech rate

The relative average duration of vowels were found to have a significant impact on the perception of a given speech rate (tempo) of a Text to Speech Synthesis System (TTS) developed for the Greek language. Even though the duration ratios vary slightly according to segmental context and word prominence, their modification beyond a certain level of tolerance, may result in the perception of a mismatch for the tempo of the modified word in comparison with the tempo selected for the rest of the phrase.