Ultrasound observations of tongue root configuration in Japanese geminated /t/

Previous ultrasound studies indicate that geminated stops in some languages are produced with a more advanced tongue position compared to singletons, due to fortition (Percival et al. 2018 and Alamri 2022). Possible cross-linguistic variations have also been reported (Percival et al. 2020 and Kwon & Ahn 2024). In Japanese, the view that there is articulatory strengthening for geminates is supported through electropalatography studies (Kawahara & Matsui 2017 and Kochetov & Kang 2017), but the tongue root configuration in geminate production has not been addressed. In this study, we integrate results from three comparable ultrasound experiments to examine the tongue root positions at the offset of the singleton and geminate /t/ closure in /C1ata/∼/C1atːa/ pairs produced by 18 native speakers of Japanese. C1 and the lexical status of the stimuli varied: nonce-words /pata/∼/patːa/, /bata/∼/batːa/, and real words /hata/ (surname) ∼ /hatːa/ “crawl-PAST.” Through a within-speaker comparison of tongue contour models, we observed an advanced tongue root in geminates for /pata/∼/patːa/ in all three speakers, but in five out of the 15 speakers for /bata/∼/batːa/ and /hata/∼/hatːa/. We discuss the possibility that tongue root advancement in Japanese geminates interacts with the need to control intraoral air pressure, which may be affected by the preceding consonant.