PROBLEM TO BE SOLVED: To perform a parameter compensation process so as to suppress deterioration of subjective quality in predictive quantization.SOLUTION: Amplifiers (305-1 through 305-M) multiply input quantized predictive residual vectors xthrough xby weighing factors βthrough β. An amplifier (306) multiplies a decoded LSF vector yof a previous frame by a weighting factor β. An amplifier (307) multiplies a code vector xoutput from a code book (301) by a weighting factor β. An adder (308) calculates a sum total of vectors output from the amplifiers (305-1 through 305-M), the amplifier (306) and the amplifier (307). If a lost-frame code Bof the current frame indicates that 'the n-th frame is a lost frame' and if a lost-frame code Bof the next frame indicates that 'the n+1-th frame is a normal frame', a changeover switch (309) selects a vector output from the adder (308).
PARAMETER DECODING DEVICE AND PARAMETER DECODING METHOD