1. A method for coding excitation signal of a target speech comprising: extracting from a set of training normalised residual frames a set of relevant normalised residual frames, said training residual frames being extracted from a training speech, synchronised on Glottal Closure Instant (GCI) and pitch and energy normalised; determining a target excitation signal from the target speech; dividing said target excitation signal into GCI synchronised target frames; determining the local pitch and energy of the GCI synchronised target frames; normalising the GCI synchronised target frames in both energy and pitch, to obtain target normalised residual frames; determining coefficients of linear combination of said extracted set of relevant normalised residual frames to build synthetic normalised residual frames close to each target normalised residual frames; wherein the coding parameters for each target residual frames comprise the determined coefficients.