A High-Precision Fatigue Detecting Method for Air Traffic Controllers Based on Revised Fractal Dimension Feature

Figure 3

Phase trajectory when saying “speed.” Here, dimension is 3. Delay is 6. This parameter setting is the same below. The right and left subgraphs of all four graphs show the phase-space trajectories of speech signals produced in the normal and fatigued states, respectively. The figures clearly indicate that the degree of speech fluctuation is significantly lower in a fatigued state than in a nonfatigued state.

(a)

(b)