In the above publication by Deng (Reference Deng2014), figure 2 has been mistakenly duplicated replacing figure 3. The publisher apologises for this error and the correct figure 3 is shown below.
Top to bottom: Original spectrogram from the test set; reconstruction from the 312-bit VQ coder; reconstruction from the 312-bit auto-encoder; coding errors as a function of time for the VQ coder (blue) and auto-encoder (red); spectrogram of the VQ coder residual; spectrogram of the deep autoencoder's residual.