Figure 12. A pump ID: 06 operation sound data of 6 dB SNR 6 dB ( left ) and − 6 dB SNR ( right ). Figure 12. A pump ID: 06 operation sound data of 6 dB SNR 6 dB (left) and − 6 dB SNR (right). Projections of the 320-dimension log-Mel spectrogram feature onto the 2D space by PCA. The blue Projections of the 320-dimension log-Mel spectrogram feature onto the 2D space by PCA. The blue and red symbols represent the normal condition and the anomalous condition, and red symbols represent the normal condition and the anomalous condition, respectively.