Pitch Estimation and Voiced–Unvoiced Classification of Speech - Digital Speech: Coding for Low Bit Rate Communication Systems - page 182

Figure 6.28 Speech waveform and (top) maximum, (middle) average, and (bot-
tom) minimum tracked energies, and the frame energy (shown by the dotted line);
energies have been shifted up

Decision-Making
Having computed the most useful voicing indicators, a combined decision
has to be made. The simplest decision-making rule is to use a majority
vote. A better decision rule could be to use a weighted combination of the
voicing indicators. Two types of weighting can be applied to produce a
combined decision. Different parameters have different degrees of reliability
in indicating the correct voicing and the weighting could be used to reflect
these variations in reliability. The weighting of parameters such as periodic
similarity and spectral tilt can be higher to reflect their greater reliability.
In addition, a second set of weightings can be used to reflect the difference
of each parameter from the optimum decision threshold. For example, the
variations of each parameter can be normalized to be 1aroundtheoptimum

threshold and these values can be used in a summation with the appropriate
weights which reflect the importance of the corresponding parameter. The

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