Digital Signal Processing Reference
In-Depth Information
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(a) A typical spectrum of babble noise
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(b) A typical spectrum of vehicular noise
Figure 9.35
Typical acoustic noise spectra
using white-noise excitation will degrade the perceptual quality by intro-
ducing an unnaturally noisy background. Therefore, in fact, the classification
algorithm detects the most suitable mode, i.e. ACELP, to synthesize back-
ground noise. However the drawback is a high average bit-rate, which may
be reduced by using a robust voice activity detection (VAD) algorithm and
comfort noise generation at the decoder end [9].
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