Signal Gain and Harmonics to Noise Ratio

Abstract

The final basic component of the speech source model is that of the intensity, volume or energy of the two main components, voiced and unvoiced parts of the speech signal. Usually, signal output energy is modelled by simple gain factors applied to the excitations of the filters. The two parts, unvoiced excitation corresponding to the residual codebook and the voiced excitation corresponding to the adaptive codebook, are most commonly multiplied with two scalar gain factors which are coded jointly. Alternatively, it is possible to encode a single output-energy gain and steer the proportion of components with a ratio-factor corresponding to the harmonics to noise ratio (HNR).