Use of formants in stressed and unstressed continuous speech recognition

Stress plays a crucial role in the understanding of speech by human listeners. However, automatic speech recognition results deteriorate in the presence of stress due to the change it causes in the speech parameters. Meanwhile, due to the vast diversity of the presence of stress in speech, a speech corpus that contains the majority of different stress conditions is difficult to obtain in real world. Therefore, other ways to improve stressed speech recognition performance have to be taken into account. In previous works, we have evaluated the effects of stress on several speech parameters such as phone durations, pitch and formant frequencies. In this paper, the use of formants in stressed speech recognition will be discussed. We have found that formants and their dynamics (slopes) are useful in improving speech recognition rates both in stressed and unstressed conditions.