Encoding and decoding methods and apparatus are described to obtain auxiliary information from an audio signal. The auxiliary information uses a plurality of frequency components residing in a plurality of code bands. The audio signal is transformed into a frequency domain representation. Characteristics of frequencies of the frequency domain representation that may contain the auxiliary information are determined. The characteristics of frequencies of the frequency domain representation in a respective one of the code bands that may contain the auxiliary information are normalized across the code band. The normalization is carried out against a characteristic of a frequency in that code band. The normalized characteristics of the frequencies representative of auxiliary information are summed to determine a sum for a frequency representative of auxiliary information. It is determined when the sum is representative of the auxiliary information.