User:Sivi Volk/EMMA (speech)

Electromagnetic Midsagittal Articulometer ...

Electromagnetic midsagittal articulometers are devices used to transduce articulatory movements during speech production, in order to reconstruct the movement of articulators. They were developed to allow for a safer, less invasive, and less expensive method of directly observing and measuring articulatory movements during speech than previous midsagittal scanning x-ray microbeam systems.

Function of EMMA devices
All EMMA systems involve two or more electromagnetic coils, which generate alternating magnetic fields at different oscillation rates around a speaker's head.

These fields alter the voltage in the transducer coils, which are attached to speech articulators (tongue, mandible, lips, palate, etc.) as well as two or more fixed reference points.

The transducer coils are attached along the midline of the vocal tract, hence "midsagittal". Wires lead from the transducer coils to various receivers.

The change in voltage over time represents the location of the transducer coils in relation to the magnetic coils and the reference coils. This allows researchers to calculate the shape and motion of articulators over time, during speech production.

History of EMMA devices
Early attempts at developing an EMMA system were frustrated by problems caused by out-of-plane tilting movements of the tongue.

Schönle and colleagues at the University of Göttingen developed a system in the late 1980s.

Joe Perkell and colleagues at MIT developed a system in the early 1990s, which uses either 2 transmitters and biaxial transducer coils, or 3 transmitters and single-axis coils. This design only allows for motion tracking in two dimensions.