Distance vs time. Acoustic and articulatory consequences of reduced vowel duration in Polish

This paper presents acoustic and articulatory (ultrasound) data on vowel reduction in Polish. The analysis focuses on the question of whether the change in formant value in unstressed vowels can be explained by duration-driven undershoot alone or whether there is also evidence for additional stress-specific articulatory mechanisms that systematically affect vowel formants. On top of the expected durational differences between the stressed and unstressed conditions, the duration is manipulated by inducing changes in the speech rate. The observed vowel formants are compared to expected formants derived from the articulatory midsagittal tongue data in different conditions. The results show that the acoustic vowel space is reduced in size and raised in unstressed vowels compared to stressed vowels. Most of the spectral reduction can be explained by reduced vowel duration, but there is also an additional systematic effect of F1-lowering in unstressed non-high vowels that does not follow from tongue movement. The proposed interpretation is that spectral vowel reduction in Polish behaves largely as predicted by the undershoot model of vowel reduction, but the effect of undershoot is enhanced for low unstressed vowels, potentially by a stress marking strategy which involves raising the fundamental frequency.