From Wikipedia,

The game also ships with a unique drum controller, the AirStrike, that allows the player to interact with the game without contact, similar to air guitaring, making for a quieter playing experience. The crescent-shaped unit, with four sensors and a bass-drum kick pedal along with additional console control buttons, is used by placing it on the floor in front of the player. The unit senses the movements in the general areas where the sensors are located, simulating the position of drums, and is able to distinguish movement between the individual drum sticks. The unit also includes support legs to bring the sensors closer to the player to help improve movement detection.

Source: Wikipedia, "Power Gig: Rise of the SixString", available under the CC-BY-SA License.