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Linear Predictive Coding (LPC) of Speech 623
FIGURE 12.12
Block diagram model for the generation of a speech signal
Given a short-time segment of a speech signal, usually about 20 ms
or 160 samples at an 8 kHz sampling rate, the speech encoder at the
transmitter must determine the proper excitation function, the pitch period
for voiced speech, the gain parameter G, and the coefficients a p (k).
A block diagram that illustrates the speech encoding system is given in
Figure 12.13. The parameters of the model are determined adaptively
from the data and encoded into a binary sequence and transmitted to the
receiver. At the receiver the speech signal is synthesized from the model
and the excitation signal.
The parameters of the all-pole filter model are easily determined from
the speech samples by means of linear prediction. To be specific, the
output of the FIR linear prediction filter is
p∑
ŝ(n) =− a p (k) s (n − k) (12.28)
k=1
FIGURE 12.13
Encoder and decoder for LPC
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