Exercise 4.1.  If you have any other software capable of spectral analysis, compare the outputs. For instance, the output of spectral analysis at the same point using Cool Edit 96 is shown in figure 4.4. Naturally, it is not different in any important respects.

Reading. Schroeder, M. R. (1985) Linear Predictive Coding of Speech: Review and Current Directions. IEEE Communications Magazine Vol. 23, No. 8. 54-61.