Mental processing demands on tongue position during rhotic production

Cognitive load may affect tongue position during speech production. Previous studies demonstrate that the tongue is influenced by the central and autonomic nervous systems [Bourdiol et al., 2013, Journal of oral rehabilitation, 40(6)] and increased cognitive load impacts front and back vowel formants [Huttunen et al., 2011, JASA 129]. Little is known about this effect, including whether it is moderated by pressure to maintain acoustic targets. North American English [ɹ] is known to allow substantial articulatory variation while maintaining a relatively stable acoustic (F3) target [Guenther et al., 1999, JASA 105]. The present study investigates variation of tongue position for North American English [ɹ] under increasing levels of cognitive load using a Stroop task [Tomassi et al., 2025, JSLHR, 1–20]. We hypothesize that under high cognitive load, the articulation of English [ɹ] may show intra-speaker variation in tongue shape. Ultrasound imaging was used to measure tongue position during speech across congruent and incongruent trials, and speech errors were filtered out. Preliminary results indicate that tongue shape varies both across and within speakers when producing [ɹ] and [Éš] across congruent and incongruent trials. Implications for speech processing will be discussed. [Work supported by NSERC.]