A fast and flexible MRI system for the study of dynamic vocal tract shaping

Abstract

Purpose To develop and evaluate a MRI-based system for study of dynamic vocal tract shaping during speech production, which provides high spatial and temporal resolution. Methods The proposed system utilizes (a) custom eight-channel upper airway coils that have high sensitivity to upper airway regions of interest, (b) 2D golden angle spiral gradient echo acquisition, (c) on-the-fly view-sharing reconstruction, and (d) off-line temporal finite difference constrained reconstruction. The system also provides simultaneous noise-cancelled and temporally aligned audio. The system is evaluated in three healthy volunteers, and one tongue cancer patient, with a broad range of speech tasks. Results We report spatio-temporal resolutions of 2.4×2.4 mm2 every 12ms for single-slice imaging, and 2.4×2.4 mm2 every 36 ms for three-slice imaging, which reflects roughly 7-fold acceleration over Nyquist sampling. This system demonstrates improved temporal fidelity in capturing rapid vocal tract shaping for tasks such as producing consonant clusters in speech, and beat-boxing sounds. Novel acoustic-articulatory analysis was also demonstrated. Conclusions A synergistic combination of custom coils, spiral acquisitions, and constrained reconstruction enables visualization of rapid speech with high spatio-temporal resolution in multiple-planes.

Intermittently tagged real‐time MRI reveals internal tongue motion during speech production

“…Motion artifacts exist in some of the current results. This is not surprising as Lingala et al pointed out that fully sampled single slice RT‐MRI cannot resolve all tongue movements, especially during faster pace speaking or those involving intrinsically faster subsystem movement such as by the tongue tip. These artifacts can be mitigated by under‐sampling and constrained reconstruction methods, which have yet to be explored in combination with tagging.…”

“…Markl et al suggested a CNR threshold of 6 for cardiac applications. Simulated is calculated as the simulated steady state signal divided by 15, as suggested by previous experiments . A threshold time can be calculated as the time span between the tag being placed and when the CNR decrease below the threshold value.…”

Characterizing Articulation in Apraxic Speech Using Real-Time Magnetic Resonance Imaging

“…By the end of the weekend, we had counted 10 Kens and 13 Georges." With recent developments in imaging technology (Lingala et al, 2016), it is possible to detect vocal fold abduction, even in the sagittal slice, of images acquired at an extremely high frame rate, allowing for use of segments that differ only in voicing.…”

“…It is likely that this signal, time locked with the consonantal gestures, arises due to rtMRI scanner noise resonating in the speaker's vocal tract. In order to ensure that these articulations are, indeed, produced without any phonation and are not whispered, utilization of the imaging technique described above (Lingala et al, 2016) to determine if sustained adduction or abduction of the vocal folds are observed at the appropriate points in time or collection of oral airflow data would be required.…”

Bilabial Substitution Patterns during Consonant Production in a Case of Congenital Aglossia

“…Speech responses were acquired using an rtMRI protocol developed specifically for the dynamic study of upper airway movements [22,23]. Experiments were performed on a GE Signa Excite 1.5T scanner with a custom eight-channel upper airway receiver coil.…”