Global InformationElectromagnetic articulography information
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.
EMA is used in linguistics and speech pathology to study articulation and in medicine to study oropharyngeal dysphagia. Other methods have been used to study articulation and ingestion with tradeoffs in the kind and amount of data available. Palatography allows the study of articulations that make contact with the palate such as some lingual consonants, but unlike EMA, palatographs cannot provide data on sounds which do not make contact such as vowels. Fluoroscopy and X-ray microbeam allow the investigation of non-contact movements of the mouth like EMA, but expose subjects to ionizing radiation which limits the amount of data that can be collected from a given participant.