Estimating tonal prosodic discontinuities in Spanish using HMM

Abstract

The tonal prosodic discontinuity estimation in Spanish is exhaustively modelled using HMM. Due to the high morphological complexity in Spanish, a relatively coarse grammatical categorization is tested in two sorts of texts (sentences from newspapers and a theatre play). The estimation of the type of discontinuity (falling or rising tones) at the boundary of intonation groups is assessed. The HMM approach is tested with: (a) modelling the observation probability with monograms, bigrams and full-window probability; (b) state duration modelling; (c) discriminative analysis of intermediate and final observation vectors and (d) penalization scheme in Viterbi decoding. The optimal configurations led to reductions of 3% or 5% in error detection. The estimation of the observation probability with monograms and bigrants leads to worse results than the ordinary full-window probability, although they provide better generalization. Nevertheless, the performance of the monograms and bigrams approximation can be enhanced if applied in combination with state duration constraints.