An Analysis of the Speech Under Stress Using the Two-Mass Vocal Fold Model

We focus on the glottal source of speech production, which is essential for understanding the behavior of vocal fold when speech is produced under psychological stress. A spectral flatness measure (SFM) is introduced, as a useful tool, to evaluate stress levels in speech. Further, the relationship between the physical parameters of the two-mass vocal fold model and the proposed stress level measurement is established. The physical parameters of two-mass model are examined and analyzed comparing with measurements in order to estimate the state of vocal folds in people experiencing stress in the future. In this paper, experiments are performed using stressed speech gathered from real telephone conversations to evaluate the stress level measurement.Results show that the SFM can detect stress and can be used as a measurement for differentiating stressed from neutral speech. Furthermore, the changes in physical parameters can be analyzed to understand the behavior of vocal folds when stress occurs.