1. A method comprising: receiving an input linear prediction parameter vector; classifying a sound signal frame corresponding to the input linear prediction parameter vector; computing a prediction vector; subtracting the computed prediction vector from the input linear prediction parameter vector to produce a prediction error vector; scaling the prediction error vector; quantizing the scaled prediction error vector; wherein: computing a prediction vector comprises selecting one of a number of prediction schemes in relation to the classification of the sound signal frame, and computing the prediction vector in accordance with the selected prediction scheme; and scaling the prediction error vector comprises selecting at least one of a number of scaling schemes in relation to the selected prediction scheme; and scaling the prediction error vector in accordance with the selected scaling scheme.