Construction of real-time MRI articulatory movement database: Applications to Japanese phonetics and future perspectives

Subjectivity of observation is the most critical issue in the study of articulatory phonetics. To address this challenge, many observational instruments have been developed, including X-ray photography and movies, X-ray microbeam, EMA, ultrasound imaging, EPG, and EGG. Among these, real-time MRI movies (rtMRI), which became practical in the 2010s, hold a special status as an observational tool that currently provides the most comprehensive and beneficial information for phonetic research. However, since the facility of rtMRI is limited and the cost of obtaining rtMRI data is not negligible, it is not readily accessible to everyone. To overcome this issue, we have constructed a database known as the Real-time MRI Articulatory Movements Database (rtMRIDB) comprising 25 speakers and covering basic combinations of articulatory movements in Japanese. The first version of the rtMRIDB became publicly available on the web in 2021. The speech organ contour data have also been available since 2025. In this presentation, we will first introduce the specifications and characteristics of this database. Then, we will explain how this database has led to revisions in the traditional descriptions of Japanese phonetics. Finally, we will conclude with a prospect of the future expansion of the database.