Prominence-based evaluation of L2 prosody

Prosody in terms of word and sentence stress is one of the most difficult features for many second language (L2) speakers to learn and it can be hypothesized that assessing the learner's prosodic abilities could provide a good measure for assessing the learners' spoken language skills in general. Automatic assessment is, however. dependent on reliable automatic analyses of prosodic features for comparing the productions between native (L1) and L2 speech. Here we investigate, whether estimated prosodic prominence levels of syllables can be used to predict the prosodic competence of Finnish learners of Swedish. Syllable level prominence was estimated for 99 L2 and 25 native Swedish utterances using continuous wavelet transform analysis with combinations of f(0), energy. and duration features. The L2 utterances were assessed by four expert raters using the revised CEFR scale for prosodic features. Correlations of prominence estimates for L2 utterances with estimates for L1 utterances and linguistic stress patterns were used as a measure of prosodic proficiency of the L2 speakers. The results show that these estimates correlate significantly with the assessments of expert raters. Overall, the results provide strong support for the use of the wavelet-based prominence estimation techniques in automatic assessment of L2 proficiency.