Electropalatography as a Research and Clinical Tool

Electropalatography (EPG) has its origin in older forms of palatography and other methods of recording details of tongue contact with the palate during speech. Earlier versions of palatography such as “direct palatography” described by Abercrombie (1957) involved spraying the roof of the mouth with a black powder (e.g., a mixture of charcoal and chocolate) and photographing the area of “wipe-off” on the palate and teeth following tongue contact for the targeted sounds. The problem with this technique was that it recorded a single snapshot only and was therefore unsuitable for examining details of tongue dynamics, for example, the changing patterns of tongue contacts as they occurred during normal continuous speech. During the late 1960s and early 1970s, the first author was working on a new form of dynamic palatography in the Phonetics Laboratory at Edinburgh University. ¹ The technique involved the subject wearing an artificial palate made of acrylic incorporating an array of silver electrodes which could respond to contacts made by the tongue. The changing patterns of contacts were displayed on a panel of light-emitting diodes and a permanent record of the patterns was obtained by a high speed cine-camera (Hardcastle, 1972).