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.
USC-TIMIT is an extensive database of multimodal speech production data, developed to complement existing resources available to the speech research community and with the intention of being continuously refined and augmented. The database currently includes real-time magnetic resonance imaging data from five male and five female speakers of American English. Electromagnetic articulography data have also been presently collected from four of these speakers. The two modalities were recorded in two independent sessions while the subjects produced the same 460 sentence corpus used previously in the MOCHA-TIMIT database. In both cases the audio signal was recorded and synchronized with the articulatory data. The database and companion software are freely available to the research community.
Stretchable device systems with suspended SnO2 nanowires (NWs) as channel materials: Oxygen plasma is used to remove the underlying polymer to float the NWs. These suspended NW field‐effect transistors exhibit high electrical performance. By adopting a neutral mechanical plane and curved interconnection, electrical performance of the suspended NW field‐effect transistors is maintained under stretching up to approximately 40%.
In speech production research using real-time magnetic resonance imaging (MRI), the analysis of articulatory dynamics is performed retrospectively. A flexible selection of temporal resolution is highly desirable because of natural variations in speech rate and variations in the speed of different articulators. The purpose of the study is to demonstrate a first application of golden-ratio spiral temporal view order to real-time speech MRI and investigate its performance by comparison with conventional bit-reversed temporal view order. Goldenratio view order proved to be more effective at capturing the dynamics of rapid tongue tip motion. A method for automated blockwise selection of temporal resolution is presented that enables the synthesis of a single video from multiple temporal resolution videos and potentially facilitates subsequent vocal tract shape analysis. Magn Reson Med 65:1365-1371, 2011. V C 2010 Wiley-Liss, Inc.
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