The activity of the cricothyroid muscle and the intrinsic fundamental frequency in Danish vowels.

The relationship between the electromyographic (EMG) activity from the pars obliqua of the cricothyroid (CT) muscle (recorded with bipolar hook-wire electrodes) and the intrinsic fundamental frequency (IF0) in high and low vowels in Danish was investigated. The test material, which consisted of 306 randomized natural words of the type C'V(:)le, imbedded in carrier sentences, was recorded by 4 native speakers of Danish. The following vowel pairs were compared: ['i-'a,'i:-'ae:, 'u:-'ae:] and ['i:-'a]. The results, which are based on visual inspection of average EMG and fundamental frequency (F0) curves, show a positive correlation between the CT activity and IF0, more specifically that the CT activity rise related to the high vowels starts earlier and in most cases more steeply than the CT activity related to the low vowels. However, a drop in F0 at the beginning of the low vowels cannot be accounted for by CT activity. This F0 drop is believed to be the result of either tongue retraction during the articulation or influence from the preceding consonant. The following conclusion is drawn: The CT muscle is a major factor in controlling IF0 in stressed high and low vowels in Danish.