MFCC circular power spectral model

We now construct an “MFCC-like" data model. The structure of MFCC is defined in the frequency-domain by the MEL band functions. Let $(N/2+1)\times K$ matrix ${\bf A}$ contain the spectral band functions. We define the circular power spectrum of an MFCC-like process as

$$\mbox{\boldmath$\rho$} _w = {\bf A} {\bf b},$$ (11.5)

where ${\bf b}$ is a $K\times 1$ vector of positive values.