Abstract: The invention proposes a method for embedding an ancillary data into a compressed audio signal. This is achieved by replacing Least Significant Bits (LSBs) in at least one frequency subband of the compressed audio signal by the ancillary data. When replacing LSB bits of compressed subband signals with the ancillary data, the subband signal is effectively modified, resulting in a different decoded output. The replaced LSB bits corresponding to the ancillary data are conveyed as part of the bitstream and can be easily extracted at the decoder. In such a way the decoder obtains the ancillary data that can be used for more advanced audio reproduction at the decoder. The compressed audio itself maintains a good audio quality despite the replacement of the LSB bits of the frequency subband, because the LSB bits do not contribute to the audible artefacts.