A block length judging circuit (120) switches block lengths based on a feature quantity obtained from an input signal. A transform circuit (200) executes transform of the signal into frequency components according to the block length. A masking threshold calculating circuit (250)calculates a masking threshold simulating the masking characteristic of psychoacoustical property for each predetermined intra-block section. An inter-block/intra-block bit assignment circuit (300) executes inter-block bit number assignment and/or intra-block bit number assignment to each Predetermined intra-block section. A vector quantization circuit (350)vector quantizes transform signal by switching codebooks (3601 to 360N)according to the assignment bit number, and also quantizes gain by using a gain codebook (370). <IMAGE>
Wide band signal encoder