30. The apparatus of claim 26 , wherein said random vector comprises a unit variance random vector.
26. The apparatus of claim 17 , wherein the speech signal is represented by a residual signal generated by filtering the speech signal with a Linear Predictive Coding (LPC) analysis filter, and wherein said plurality of encoding means includes a NELP encoding means comprising: energy estimator means for calculating an estimate of the energy of the residual signal, and encoding codebook means for selecting a codevector from a first codebook, wherein said codevector approximates said estimated energy; and wherein said plurality of decoding means includes a NELP decoding means comprising: random number generator means for generating a random vector, decoding codebook means for retrieving said codevector from a second codebook, multiply means for scaling said random vector based on said codevector, such that the energy of said scaled random vector approximates said estimate, and means for filtering said scaled random vector with an LPC synthesis filter, wherein said filtered scaled random vector forms said synthesized speech signal.