
A command to (re)construct a MelSpectrogram object from the selected MFCC object.
The values P_{j} in each frame of the MelSpectrogram will be constructed by applying the inverse Discrete Cosine Transform to the corresponding frame of the MFCC object:
P_{j} = 2/N (c_{0}/2 + Σ_{k=1}^{N1} c_{k} cos (πk(j0.5)/N))), 
where N represents the number of filters that were used to get the MFCC object, j runs from 1 to N, and coefficients c_{k} with k less than fromCoefficient and k larger than toCoefficient take zero values in the evaluation.
© djmw, October 23, 2014