Although the acoustic characteristics of Lombard speech have been widely studied, the relationship between this kind of production and the inter-utterance rest position (IURP) of the tongue has not been sufficiently investigated. In this study, we focus on the differences in IURPs between normal and Lombard speech. In our experiments, Japanese native speakers are presented with alternating sequences of silence and noise (30 s each) at 78 dB(A) via noise-cancelling earbuds while producing combinations of digits and moras. These utterances are recorded simultaneously with a microphone and an ultrasonic probe. In a previous study involving a single young male Japanese speaker, it was found that the tip of the tongue was about 2.0 mm lower in noisy conditions. This lowering of the tip of the tongue may indicate jaw lowering, which is consistent with louder speech production. We predict that similar effects in IURPs will be observed with a larger sample. This research promotes a better understanding of articulatory aspects and contributes to speech science and the development of efficient tools for articulatory analysis.
Komagata et al. (2025) studied this question.