Figure 10. A pump ID: 06 operation sound data of 6 dB SNR ( left ) and − 6 dB SNR ( right ). Projections of the 64 × Figure 10. A pump ID: 06 operation sound data of 6 dB SNR (left) and − 6 dB SNR (right). Projections of the 64 × 313 log- 313 log-Mel spectrogram feature onto the 2D space by PCA. The symbols of blue and red represent the normal condition, Mel spectrogram feature onto the 2D space by PCA. The symbols of blue and red represent the normal condition, and and anomalous condition, anomalous condition, respectively.