Why encode pitch as one-hot encoding instead of ordinal encoder? looking at the state-of-the-art publications on deep learning for synthesizing audio one can see that they always resort to encoding pitch as a one-hot vector. I'm curious what the advantage is on doing this, since pitch (frequency) fits naturally as a scalar value and one could reduce network dimensionality by encoding it as such. 

The papers I've studied are:

GANSynth: Adversarial Neural Audio Synthesis

Neural Audio Synthesis of Musical Notes with WaveNet Autoencoders
Because average of encoded pitches is not the encoded class.

Look at this example:

LabelEncoder can turn [dog,cat,dog,mouse,cat] into [1,2,1,3,2], but then the imposed ordinality means that the average of dog and mouse is cat. Still there are algorithms like decision trees and random forests that can work with categorical variables just fine and LabelEncoder can be used to store values using less disk space.