Browsing by Subject "formantti"

Goals: Vowels are defined as their unique formant pattern based on their vocal tract configuration, according to acoustic theory of speech production. Simplified, high frequency F1 values are inversely related to the height of the tongue and high F2 values are high when the tongue is in front of the mouth cavity. Then, F1 is responsible for vertical and F2 for horizontal movement of the tongue. The aim of this study was to examine articulation of the Finnish vowels [i] and [ɑ], and also compare them to the two lowest formants: will the speakers produce vowels in the same manner of articulation. Methods: Four MRI scanned subjects, two men and two women, were included in this study. Half of them were normal speakers and other half orthognatic patients. MR-pictures were 3D-pictures (DICOM), and measuring was made with Osirix-program using nine articulatory measurement points. Also five lowest formants of the speech signal were measured with Praat-program. Regressions between articulatory variables were statistically examined as well as connections between articulatory and acoustic data. Linear mixed-effects model was used on the latter. Articulatory data was normalized for the comparison because of individual anatomy of the speakers Results and conclusions: Differences between speakers were noticed. Basically, articulation of normal speakers was stable, but orthonatic patients had extreme or versatile articulatory positions instead. Statistical testing revealed that there where positive and negative correlations between articulatory measurement points. Speaker or vowel dependent differences as well as clear synergism were found. An important observation was that the tongue root was a vowel dependent separator. There was also found a considerable connection between horizontal tongue position and F2. However, the sound environment of the MR-imaging may have caused the Lombard effect and that is why the results must be considered with caution. Comparing them to normal speech is not recommended. In future, it would be suggested to make the articulatory and acoustic measuring methods more accurate, and study if differences between normal speakers and orthonatic patients can be generalized. Also it would be recommended to gather more data of the other Finnish vowels and their articulatory positions.