Real-time MRI datasets, where 460 sentences were pronounced by 4 and 10 speakers, are presented in 22 and 16, respectively. In this context, multiple databases exist for English speakers. Since the technologies listed above are not easily available, data sharing could greatly accelerate research in the field.

Another approach, which does not necessarily assume a non-cartesian encoding, was used for dynamic 3D imaging of the vocal tract 14, 21. The technique 20 makes use of radial sampling and the regularized nonlinear inversion reconstruction. In 18, 19, a radial encoding scheme was used together with a compressed SENSE reconstruction. and was thereafter combined with sparse-SENSE constrained reconstruction methods 8, 17. A spiral encoding scheme was applied in 15, 16. This approach has been employed by several research groups to study speech. Acquisition can be sped-up by usage of non-cartesian (generally undersampled) schemes which ensure good coverage of the k-space centre. Real-time MRI allows high spatio-temporal resolution without repeating and is usually based on spoiled gradient echo sequences 8, 13, 14. However, this method requires several identical repetitions of the same target utterance, which leads to artifacts in case of non-periodicity, and increases acquisition time.

One of the techniques allowing a reasonable spatio-temporal resolution of recorded speech, is cine-MRI 11, 12. However, MR imaging of a speaking person is a challenging problem due to the fast motion of articulators. Contrarily to other techniques such as ultrasound, which fails to visualise the articulators separated from the sensor by air, or EMA which provides only the sensors’ trajectories glued on the upper vocal tract articulators, MRI succeeds to visualise the whole vocal tract. Nowadays, magnetic resonance imaging (MRI) holds one of the leading positions as a data acquisition method in speech sciences 7, 8, 9, 10 due to its non-invasiveness and absence of long-term health hazards. Information on motion can be obtained using different methods including electromagnetic articulography (EMA) 4, X-ray 5 and ultrasound imaging 6.

The investigation of the movement of speech articulators has a number of applications including study of speech production 1, speech recognition 2, as well as some medical applications: diagnosis and rehabilitation of abnormal speech and swallowing, study of orto-facial structures implicated in sleep apnoea syndrome 3.

Time machine sounds