CATEGORIZING [S], [S] AND INTERMEDIATE ELECTROPALATOGRAPHIC PATTERNS - NEURAL NETWORKS AND OTHER APPROACHES

We consider two approaches to the interpretation of EPG data, using ma terials designe for the investigation of [s]-[f] assimilations across word boundaries, as in boss Shep. A contact index is based on electrod e contact in different row groups, whereas a neural network is used to determine patterns of contact. Both approaches are speaker sensitive, reflecting the wide variation in [s] and [f] articulation between spe akers. The advantage of the neural net analysis is that the investigat or need not make any assumptions about the relative value of specific electrodes or groups of electrodes. We found that the 'hand-selected' index, in general, modelled linguopalatal movement for all degrees of [s]-[f] assimilation better than the neural net. However, the neural n et very successfully characterised stable /s/ and /f/ and has the pote ntial to give an accurate representation of intermediate assimilatory cases, if trained on a more varied input set than the rather limited o ne used in this experiment.