1. A device for quantizing a gain of a fixed contribution of an excitation in a frame, including sub-frames, of a coded sound signal, comprising: an input for a parameter representative of a classification of the frame; an estimator of the gain of the fixed contribution of the excitation in a sub-frame of said frame, wherein the estimator is supplied with the parameter representative of the classification of the frame; and a predictive quantizer of the gain of the fixed contribution of the excitation, in the sub-frame, using the estimated gain.