Integrated magnetic resonance imaging methods for speech science and technology

Abstract

This presentation introduces our integration of magnetic resonance imaging (MRI) techniques at ATR Brain Activity Imaging Center (Kyoto, Japan) toward research into speech science and technology. The first breakthrough in our application of MRI to speech research was the motion imaging of the speech organs in articulation using a cardiac cine‐MRI method. It enables us to acquire information in the time‐space domain to reconstruct successive image frames using utterance repetitions synchronized with MRI scans. This cine‐technique was further improved for high‐quality imaging and expanded into three‐dimensional (3D) visualization of articulatory movements. Using this technique, we could successfully obtain temporal changes of vocal‐tract area function during a Japanese five‐vowel sequence. This effort also contributed to developing other techniques to overcome the limitations of MRI, such as the post‐hoc inclusion of teeth images in 3D volumes or the phonation‐synchronized scan for crystal‐sharp static imaging. Further, a custom high‐sensitivity coil was developed to visualize the fine structures of the lip muscles and laryngeal airway. The potentials of new MRI approaches such as ultra‐high‐resolution imaging with a higher‐field scanner or real‐time motion imaging during a single utterance will be discussed toward future contributions to speech science and technology.