Apart from its dependence on the speaker's gender (F(1,178)=946.867, p <0.0005) the fundamental frequency[6] is influenced by stress and vowel type. The effect of stress is significant for both male and female speakers (ANOVA with repeated measures in view of stress, tenseness and vowel type factors: F(1,80)=13.242, p< 0.0005 for males, F(1,60)=33.397, p<0.0005 for females). The F-ratio for the vowel type is given as: F(4,60)=3.548, p=0.012 for females and F(4,80)=7.184, p<0.0005 for males. The effect of stress on the fundamental frequency is significant for all vowels apart from /a/ for females, whereas for males the distinction between stressed and unstressed vowels is significant only for /u/ and /i/ (p=0.09 for the latter). This is partially supported by Jessen et al. (1995) who detect a dependency of F0 on stress, although some differences were found in the direct comparison. Following their classification of tokens within tense/lax and stressed/unstressed groups significant differences in F0 are found for:
a) male speakers:
b) female speakers:
Indeed, "[...] F0 [...] do[es] not contribute with much reliability to the expression of stress" (Jessen et al., 1995:4:431). It can also hardly be expected that other parameters describing the glottal action will contribute more to expression of stress. As stated in section 15.1, the most reliable correlate of word stress in German is duration.