EPG bidimensional data reduction.
A new method of electropalatographic (EPG) data reduction is proposed. It uses the so-called discrete cosine transform for representing an EPG pattern as a weighted sum of elementary 'pictures'. It is shown that several of these pictures can be considered as being articulatorily relevant. The respective contributions of these pictures to the spatial arrangement of the linguopalatal contacts are given by transform coefficients which are used here as a set of new EPG indices: the scaled sum of contacts index (SSU), the left-right asymmetry index (LRA), the alveolar-palatal index (APA) and the lateral-median index (LME). It is shown that the information extracted from an EPG pattern by means of these indices is maximised. Because of its robustness, this method could be usefully employed in studies on articulatory disorders.
D004568:Electrodiagnosis / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D010159:Palate / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D013068:Speech Production Measurement / Q000379:methods*