Speech Production Patterns in Producing Linguistic Contrasts are Partly Determined by Individual Differences in Anatomy.

This study explored correlations between (a) measures of vocal tract anatomy and (b) measuresof articulatory/linguistic contrasts in vowels and coronal fricatives. The data for the study comefrom the Wisconsin X-Ray MicroBeam Database (Westbury, 1994). The anatomical measuresincluded vocal tract length, oral cavity length, palate size and shape, as well as measures ofmaximal tongue protrusion and jaw wagging amplitude. Measures of the articulatory vowelspace included the range of x and y location at vowel midpoints for four pellets on the tongue,the interpolated highest point of the tongue, and the locations of pellets on the upper and lowerlips and to the lower incisor. For each of these clouds of vowel midpoint measurements, theorientation of variation was also measured. For fricatives, measures of tongue advancementand tongue tip lowering were taken. The results showed that the articulatory vowel space wasrelated to both the length of the vocal tract, and to the shape of the palate, while fricativevariation was related to palate parameters alone. In simple correlations, the percentage ofarticulatory variance between segments that could be predicted by anatomical characteristicswas modest; never more than 36% for vowels and 25% for fricatives. Canonical correlationanalysis found two anatomical factors that predict articulatory patterns jointly in vowels andcoronal fricatives. The first canonical variable found a relationship between vocal tractlength/palate depth and vowel tongue vertical range and jaw motion. Talkers with long vocaltracts and deep palates showed large tongue vertical range and small jaw range. The secondcanonical variable found a relationship between palate depth and tongue tip raising in coronalfricatives. Talkers with more shallow palate tended to have a tongue-tip up posture in fricatives. Phonetic tagging for the XRMBDB is made publicly available by this project.