Since Fraunhofer developed the MP3 compression method for audio, it has achieved extremely widespread. The format is now many years old and several variants, including mp3PRO, has been developed since, just as there are different formats that are better, eg. AAC and Ogg Vorbis.
Now the company Thomson is presenting a new variant of MP3, which compresses without quality loss. Usually, the high compression in MP3 is obtained by remove audio that is very difficult to hear for the human ear. The new format, which Thomson has baptized MP3HD, can compress audio 30-70% which isn’t as efficiency as MP3, but it does so without compromising the quality.
MP3HD files consist of two layers of data. One layer is an ordinary MP3 file with a quality loss, and a layer with the additional data needed to make sound complete. This means that MP3HD files are compatible with all MP3 players, but only one layer; wants to hear the sound loss-free, so you need a MP3HD player.
You can read more about MP3HD on All4MP3.com where you can also download software to create its own MP3HD files.