A SOM-Based Analysis of Early Prosodic Acquisition of English by Brazilian Learners: Preliminary Results

Silva from State University of Piauím, Brazil, presented in his poster if transfer of word stress from first language to the second language can be analyzed by using Self-organizing map(SOM).
They analyzed how stress patterns transfer from first learned language to second language among Brazilian students. The first language was Brazilian Portuguese as the foreign language was English. They wanted to see if SOM would be able to organize the speakers in the groups according to how much they transfer stress pattern and have other linguistic similarities.

The corpus used was composed of interview recordings with 30 students. Students were asked to utter 30 different English sentences containing situations where certain words act sometimes as a verb or as a noun. Because in English some words are pronounced differently depending are they a verb (obJECT) or noun (OBject). These kind of words are investigated because English and Brazilian Portuguese stress patterns are significantly different in these cases. In the poster it was only presented results obtained for the sentence "I object to going to a bar", where the analyzed word was the verb "obJECT". So the errors while pronouncing this word occur when it is pronounced as a noun instead of a verb.

To make the network, SOM used only the information provided by the Linear Predictive Coding coefficients. So no prior linguistic knowledge were used nor SOM was trained. After constructing map, label information was inserted for the result analysis.

It was discovered that by analyzing the resulting U-matrix, two clusters could be seen clearly. They confirmed that speakers were organized according to similarities on prosodic features. So the larger one was the group that transfers the Brazilian Portuguese stress pattern into English and the smaller group that didn't.

Inside the groups can be smaller subgroups which when closely examined in isolation might reveal more about the linguistic analysis of the speaker's utterances. Next Silva and co. will develop experiments to analyze these subgroups. They hope that in the future they could develop a tool for determining the language proficiency level classification in foreign languages.