Sony has rolled out its egg-shaped Rolly music device in the US, but consumers will have to shell out $400 to get their hands on the device.

The music player is a palm-sized device that rolls and spins as though it is 'dancing' to the music.

Rolly features 180-degree horizontally opposed stereo speakers, which means that listeners can enjoy high quality sound from nearly anywhere in the room as the sound reverberates from the surface on which the device is placed.

Using robotic technologies and artificial intelligence, the device is designed to move its small "arms, shoulders and wheels" to the beat of the music, while a repertoire of about 700 colours adds to the impact of the motion.

To choreograph an original routine, the unit comes with Rolly Choreographer software. Motions can either be created automatically by the software for a specific song, or users can create customised choreography for a creative twist.

Once the choreography has been created, the software simulates how the device will move so that users can preview the dance moves on a PC before transferring the routine to the unit.

"Rolly has the ability to attract your attention as soon as you turn it on," said Brennan Mullin, vice president of audio marketing at Sony Electronics.

"It is a tremendous example of what can happen when entertainment and technology merge."