This study examined the effect of context on the association between formant trajectories and tongue and lip kinematics in the American English diphthongs /aɪ/ and /aʊ/. Seventeen native speakers of American English had electromagnetic sensors placed on their tongue and lips to record kinematic signals that were time-aligned with the corresponding acoustic recording. Speakers produced the diphthongs in isolation, in a single word rVl context, in a phrase hVd context, and in a sentence context. Kinematic data and the F1 and F2 trajectories were extracted from the middle 50% of each diphthong production. To allow direct comparison of signals with different units of measurement, all data were converted to z-scores. The z-score records were plotted together on common axes. For each tracked sensor from each diphthong production, an absolute difference between the kinematic and acoustic variables was calculated. Average z-score difference sums were calculated for each speaker's /aɪ/ and /aʊ/ production in each context, and this measure was called the Acoustic Kinematic Disparity Index (AKDI). A repeated measures ANOVA was used to test for main context effects on the AKDI, with concurrent contrasts to test for differences between the baseline (isolated diphthong) condition and the more complex phonetic contexts. The results revealed that context has a significant impact on acoustic and kinematic relationships. The sentence context resulted in the highest number of significantly different AKDI values when compared to the isolated condition, the single word rVl context resulted in the second highest number, and the phrase level hVd context resulted in the least differences. These findings suggest, therefore, that more complex phonetic contexts have a greater effect on the acoustic and kinematic relationship. These findings imply that caution is warranted in relying on acoustics to draw inferences about articulator movements in complex phonetic contexts. These results further indicate that the investigation of sounds produced in one context does not necessarily allow a straightforward generalization to other contexts.



College and Department

David O. McKay School of Education; Communication Disorders



Date Submitted


Document Type





formants, diphthong, acoustic, kinematic, articulation, phonetic context