This is a quote from the Yamaha email I received a few minutes ago:

"In addition to the above, the PSR-S950 features Yamaha's new Audio Style technology that brings live drums and percussion to Yamaha’s Guitar Enhanced Style engine and now supports MP3 playback ⎯ both customer-requested. From Tyros4, Vocal Harmony 2 augments your singing with 3-part harmonies and effects. The PSR-S950 can put your favorite song (audio) in the key of your choice with a very cool pitch shift feature that lets you change the key without changing the tempo, and includes a Vocal Cancel function."