Intrinsic F0 differences for German tense and lax vowels

This study examines the vowel-intrinsic fundamental frequency (IF0) for tense and lax vowels in German: These show a similar F0 but differ in their articulatory vowel height. This is contrary to commonly accepted biomechanical theories explaining IF0 by a physiological linkage between the upper vocal tract and the larynx. To examine this phenomenon, acoustic, electroglottographic and articulatory data were recorded for three German speakers producing the tense vowels /i u / and their lax counterparts. Results for vowel mid, onset and offset showed that the articulatory positions significantly differed for tense-lax vowel pairs but the measured F0 was similar. A stepwise regression procedure selected the vertical tongue back sensor to explain the largest amount of the variance between the vowel F0 values. Correlation and regression values of both tense and lax high versus low vowels were high and significant. In contrast, regarding the tenseness difference, correlation and regression analyses between the vertical tongue back sensors and the corresponding F0 values were weak and non-significant. Thus, biomechanical IF0 theories can not account for the described tenseness phenomenon. Other mechanisms seem to be responsible, i.e. an active rise of F0 by the speaker to differentiate between tense and lax vowels.