Changes in frequency spectrum of vowels due to psychological stress

A significant part of information carried in speech signal refers to the speaker expressing their personality, transferring emotions, and reflecting situations such as fatigue, stress or some medical problems. This paper deals with speech signal spoken by speaker under psychological stress. A classification of various states of stress and the corresponding type of stressor is defined. For use in our experiments, a new database of speech under stress consisting of data collected during oral examinations at our university was created. Long-time changes of fundamental frequency and short-time changes in spectrum of vowels due to exam stress were investigated. The primary goal of the study reported here is to give an introduction to the problem “speaker´s stress and speech signal”.