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

Figure 10

The FD comparison of the detail coefficients of each layer of the speech signal in two states. Blue line indicates normal, and red line indicates fatigue: the (a) first layer, (b) second layer, (c) third layer, and (d) fourth layer.

(a)

(b)

(c)

(d)