Voice Activity Detection - Digital Speech: Coding for Low Bit Rate Communication Systems - page 360

rates of IS-127, the upper two rates, 1 and 1/2, have been assumed to be voice
active and the lowest rate, 1/8, is treated as voice inactive.
Performance in a vehicle noise environment are shown in Figures 10.8
and 10.9, and performance for babble noise are shown in Figures 10.10

40

35

30

25

20

15

10

5

0

5 10 15 20 25

Noise level (SNR dB)

G.729B GSM-EFR IS-127 AMR1 AMR2

Figure 10.8 Comparison of speech detection error rates against various vehicle
noise levels

30

25

20

15

10

5

0

5 10 15 20 25

Noise level (SNR dB)

G.729B GSM-EFR IS-127 AMR1 AMR2

Figure 10.9 Comparison of silence detection error rates against various vehicle
noise levels