# Spectral Envelope from MFCC

I'm obtaining MFCC by using the function wave2mfcc from the Speech and Audio Processing library (SAP) from here http://mirlab.org/jang/matlab/toolbox/

The steps follows the procedure:

• Take the Fourier transform of (a windowed excerpt of) a signal.
• Map the powers of the spectrum obtained above onto the mel scale, using triangular overlapping windows.
• Take the logs of the powers at each of the mel frequencies
• Take the discrete cosine transform of the list of mel log powers, as if it were a signal

As I have previously read, the MFCC are the spectral envelope of the signal, but I don't know how to relate the coefficients with the envelope.

For example, if I have a signal 'example.wav'

[signal fs] = wavread('example.wav'); figure(1); plot(log(abs(fft(signal))); mfcc = wave3mfcc(signal,fs); figure(2); plot(mfcc):

As I understand the MFCC should have the shape of the figure 1, but in my case it doesn't, maybe I'm missing some step.

Can anybody tell me please how to relate them and being able to graph?