Passage: The series was also slated to be adapted into a series of video games, developed for the Nintendo DS, PlayStation Portable and PlayStation 2 platforms, which was published by Namco Bandai Games. All three games have been available in only Japanese, although an incomplete unofficial patch for the Nintendo DS game exists on the internet that partially translates the game into English. A release on the Wii platform was cancelled for unknown reasons.The official website for the first Nintendo DS game launched on July 16, 2007, with the game being released a few months later on October 25.A second game, titled Code Geass: Lelouch of the Rebellion Lost Colors, was developed for the PlayStation Portable and PlayStation 2, and released in Japan on March 27, 2008. It is a visual novel game which follows a new protagonist named Rai (ライ), who suffers from amnesia. He has a Geass ability similar to Lelouch's, but activated by voice.

Question: How is Rai's power activated?
voice