AAC
AAC, Advanced Audio Coding, is the audio compression method DAB+ uses. It keeps sound quality high at a low data rate.
AAC is short for Advanced Audio Coding. It is a method of compressing sound so that it needs far less data than the original, with little audible loss at a reasonable bit rate.
DAB+ uses a variant called MPEG-4 AAC+, according to dabplus.ch. This is the reason one frequency block can carry more programmes than with the older DAB system. The radio decodes the signal and turns it back into sound.
AAC is also used for audio in many other places, such as streaming services. A radio that lists AAC in the specifications is not automatically a DAB+ radio, so check for the DAB+ label.