New technologies to improve surround sound using personal players and the MP3 format have been announced.

Developed by the Fraunhofer Institute for Integrated Circuits IIS and Thomson, the MP3 SX (MP3 Stereo eXtended) allows for the enhancing of MP3 stereo files for multi-channel playback, while Ensonido software provides portable MP3 surround sound using stereo headphones.

"Traditionally, surround sound has been primarily limited to loudspeaker setups in living rooms or theatres. With the Ensonido technology, the individual listening experience through portable MP3 Surround players and stereo headphones is enhanced," the partners promise.

In order to do this the technology uses an acoustic model to simulate the natural transmission of multi-channel sound from the loudspeakers to the human ear.

The backwards-compatible technology enables high-quality surround sound at bit rates comparable to those currently used to encode stereo MP3 material. A legacy MP3 device plays back MP3 Surround as high quality stereo.

Licensing of the new technology - a demo version of which is available online - will be handled by Thomson. The technology will be demonstrated at CES.