  In this work, we introduce NU-Wave, the first neural audio upsampling model
to produce waveforms of sampling rate 48kHz from coarse 16kHz or 24kHz inputs,
while prior works could generate only up to 16kHz. NU-Wave is the first
diffusion probabilistic model for audio super-resolution which is engineered
based on neural vocoders. NU-Wave generates high-quality audio that achieves
high performance in terms of signal-to-noise ratio (SNR), log-spectral distance
(LSD), and accuracy of the ABX test. In all cases, NU-Wave outperforms the
baseline models despite the substantially smaller model capacity (3.0M
parameters) than baselines (5.4-21%). The audio samples of our model are
available at https://mindslab-ai.github.io/nuwave, and the code will be made
available soon.
