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Department of Linguistics

SPEECH PHYSIOLOGY


Read these notes in conjunction with the
Workshop Video


Electropalatography (EPG)

Jonathan Harrington, 2001

Basic operation

Electropalatography allows tongue-palate contacts to be detected as a function of time from an artificial palate worn by the subject.

The Palate

A palate has to be made separately for each subject

The 62 electrodes cover the region from behind the upper front teeth to the hard/soft palate junction.

The Electrodes in the Palate

The electrodes conduct an electrical current that is passed through the subject's body (via a hand-held electrode). When the tongue touches any electrode, the current passes from the tongue into the electrode.

The Computer Display

When the tongue touches an electrode in the palate, a cell is filled on the corresponding position on a palatogram. Palatograms are typically obtained 1 per 10 milliseconds.

Figure1: Relationship between the palate and electrode placement

Figure 2: The division of the palate into articulatory zones

Figure 3: The relationship between electrode placement and the palate

Figure 4: A palate and the dental/palate impression used in its manufacture. Image source: Department of Speech and Language Sciences, Queen Margaret College, Clerwood Terrace, Edinburgh

Figure 5: A palate in place in the mouth of the subject. This palate was made specifically for this person. Image source: University of Kent at Canterbury (http://medical.ukc.ac.uk/research/EPG/EPG.htm)

Figure 6: A typical computer readout, an "electropalatogram". Image source: University of Kent at Canterbury (http://medical.ukc.ac.uk/research/EPG/EPG.htm)

Some applications of electropalatography

1. Basic speech research - e.g., coarticulation, fast speech effects

2. Assessing and describing certain kinds of speech disorders

3. As a speech therapy tool - The EPG system allows information to be given to the subject about tongue-palate misarticulations.

Investigation of the Articulatory Patterns of Young Adults with Down Syndrome using Electropalatography

Figure 7: Contact pattern for /l/ in a normal subject (top) and three subjects with down syndrome (lower three panels). Image Source: Christine Hamilton (http://www.downsnet.org/library/dsrp/artic_prob/)

The Treatment of a Severe Ataxic Dysarthria using Electropalatography

Figure 8: Severe Ataxic Dysarthria: A single case study. Image Source: Alison Main, Steve Kelly and Graham Manley (http://medical.ukc.ac.uk/research/EPG/Cb/CB.html)

Figure 9: Viewing palatal contacts as a function of time. Image source: Phonetics Laboratory, UCLA

Figure 10: 3D view of palatal changes as a function of time. Image source: Cheng Cheng Saw Tan , Phonetics Laboratory, UCLA