ENCODER, DECODER, ENCODING METHOD, DECODING METHOD, AND ASSOCIATED PROGRAMS

An encoder comprises: a first encoding unit (102) that encodes a low-band signal having a frequency lower than or equal to a predetermined frequency from a voice or audio input signal to generate a first encoded signal, and decodes the first encoded signal to generate a low-band decoded signal; a second encoding unit (106) that encodes, on the basis of the low-band decoded signal, a high-band signal from the voice or audio input signal having a band higher than that of the low-band signal to generate a high-band encoded signal; and a first multiplexing unit (103) that multiplexes the first encoded signal and the high-band encoded signal to generate and output an encoded signal, wherein the second encoding unit (106) calculates an energy ratio between a high-band noise component, which is a noise component of the high-band signal, and a high-band non-tonal component of a high-band decoded signal generated from the low-band decoded signal and outputs the calculated ratio as the high-band encoded signal.