 The SRI deep neural network was then deployed in the Nuance Verifier, representing the first major industrial application of deep learning.The principle of elevating "raw" features over hand-crafted optimization was first explored successfully in the architecture of deep autoencoder on the "raw" spectrogram or linear filter-bank features in the late 1990s, showing its superiority over the Mel-Cepstral features that contain stages of fixed transformation from spectrograms.The raw features of speech, waveforms, later produced excellent larger-scale results.