An audio signal encoding apparatus is constructed by: means for separating an input audio signal into a plurality of hierarchical data on the basis of a frequency; a plurality of encoding means for respectively encoding the plurality of hierarchical data; and error correction encoding means for adding an error correction code to an output of each of the plurality of encoding means, wherein the error correction encoding means raises error correcting ability which is caused by the error correction encoding for the hierarchical data on the low band side among the plurality of hierarchical data than that for the hierarchical data on the high band side. A bit allocation amount may be determined in accordance with a scale factor and a psychological auditory sensation model. Additionally, the busyness degree of a transmission path may be detected and a predetermined band or bands of the hierarchical data to be decoded or used by a reception side may be selected in accordance with the busyness degree.
Audio signal coding with hierarchical unequal error protection of subbands