Lip and tongue movements during phonetic sequences: analysis and definition of normal values

Precise knowledge of lip and tongue movements is limited. Conventional investigative methods do not allow for their precise representation and analysis. In the present study, electromagnetic articulography (EMA) was used to define normal values for lip movements based on consonant-vowel-consonant (CVC) sequences and for tongue movements based on vowel-consonant-vowel (VCV) sequences. The study population included 25 volunteers (11 males and 14 females) with a median age of 26 (23 to 29) years. An EMA unit was used to conduct the measurements. For this purpose, the volunteers repeated a number of VCV and CVC text sequences 10 times each during two different body positions (upright and relaxed). Statistical analysis (including Bland and Altman's measurement error, non-parametric Wilcoxon rank score testing, and analysis of variance) of distance and time variables resulted in a small measurement error. There was no effect of different body positions on measurement error. Gender was found to have a significant effect on the values measured (67 versus 17 per cent of variables related to distances in CVC versus VCV sequences and 38 versus 75 per cent of variables related to intervals in CVC versus VCV sequences). This finding did not, however, hold true for any of the other parameters investigated as potential influencing factors. EMA is capable of providing valuable information about lip and tongue movements and any pathological dysfunctions involved.