An apparatus for encoding data includes adaptive bit allocation encoding circuitry that normalizes frames of input spectrum data into transform frames in accordance with normalization coefficients and number of quantization step information. Quantized data encoding circuitry encodes each transform frame of normalized spectrum data with at least one selected code table of a plurality of code tables in accordance with a code table selection signal. Code train generation circuitry generates a code train that includes the encoded normalized spectrum data and information indicative of the at least one selected code table and of the normalization coefficients and number of quantization step information in accordance with which the encoding circuitry normalizes each frame of input spectrum data. Control circuitry generates the code table selection signal, the number of quantization step information, and the normalization coefficients in response to the input spectrum data.