Study of time and frequency variability in pathological speech and error reduction methods for automatic speech recognition
Óscar Saz, Antonio Miguel, Eduardo Lleida, Alfonso Ortega, Luís Buera · 2006
In this work, we study the variations in the time and frequency domains inside a Spanish language corpus of speakers with nonpathological and pathological speech. We show how pathological speech has a greater variability in the duration of the words than non-pathological speech, while in the frequency domain we show that the vowels confusability increases by a 18%. The baseline experiments in Automatic Speech Recognition (ASR) with this corpus demonstrate that this variability causes a loss in the performance of ASR systems. To reduce the impact of time and frequency variability we use a recent Vocal Tract Length Normalization (VTLN) system: MATE (augMented stAte space acousTic modEl), as a way of improving the performance of ASR systems when dealing with speakers who suffer any kind of speech pathology. Experiments with MATE show a 17.04 % and 11.19 % WER reduction by using frequency and time MATE respectively. 1.