Electromagnetic articulography

Electromagnetic articulography (EMA) is a method of measuring the position of parts of the mouth. EMA uses sensor coils placed on the tongue and other parts of the mouth to measure their position and movement over time during speech and swallowing. Induction coils around the head produce an electromagnetic field that creates, or induces, a current in the sensors in the mouth. Because the current induced is inversely proportional to the cube of the distance, a computer is able to analyse the current produced and determine the sensor coil's location in space.