Digital Signal Processing Reference
In-Depth Information
ground conditions. The hybrid coding algorithm described has three modes,
and two bits are allocated to transmit the mode. Therefore an additional
mode may be added to further improve the speech quality. The quality of
speech corrupted by acoustic noise can be improved by using the additional
mode as another harmonic mode with a constant voicing frequency marker,
e.g. 80% of the spectrum is voiced. Figure 9.37 depicts the spectrum of speech
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(a) Spectrum of corrupted voiced speech
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(b) synthesized speech, 80% voiced
Figure 9.37
Speech corrupted with babble noise (10dB SNR)
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