Efficient LPC Quantization Methods - Digital Speech: Coding for Low Bit Rate Communication Systems - page 139

1.3

f
g

1.2

1.1

1

0.9

0.35 0.45 0.55 0.65 0.75

Prediction Parameter

Figure 5.30 Average SD performance curves for a range of MA prediction
parameters

Table 5.15 Performance comparison of the new and classical
LSF extraction with quantization
Prediction Average 2 dB outlier 4 dB outlier WMSE

parameter SD (dB) (%) (%)

g

0.5 0.926 0.036 0 7.85E-05

f 0.4 1.031 0.23 0 9.66E-05

As the WMSE, average SD and percentage of 2 dB outliers is significantly
lower for the newmethod, bit savings can be achieved whilst maintaining the
same performance as the classic LSF VQ. The percentage of 4 dB outliers is not
shown since it was zero in all cases. Other bit combinations in a three-stage
MSVQ are shown in Table 5.16 where the new method has a clear advantage.
Figures 5.32-5.35 present the results obtained for WMSE, average SD (ASD)