@Kzyh I dont think so. They say

However, we also investigated augmenting the frequency-domain spectra with timedomain
information to improve classification. In particular, the zerocrossing rate (ZCR) has been shown to be an effective feature for differentiating breath events from unvoiced fricatives [25, 13] and have also been of interest for detecting overlapped speech [26]. It is defined as the number of times the audio waveform changes sign divided by the total number of samples in the window.

and more importantly

We added ZCR as another image channel to each spectrogram cell

So the input shape is fine I think.