Feature Extraction Method for Hidden Information in Audio Streams Based on HM-EMD

Figure 5

HACFS feature distribution in 3D space. (a) IMF1 of bus and airport. (b) IMF1 of metro and pedestrian. (c) IMF1 of park and shopping mall. (d) IMF1 of square and traffic. (e) IMF2 of bus and shopping mall. (f) IMF2 of metro and airport. (g) IMF2 of tram and park. (h) IMF2 of traffic and pedestrian.

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