An inlet door assembly and method for reducing noise from an auxiliary power unit (APU) contained within an aircraft housing is provided. The inlet assembly includes an inlet duct, an actuator, and a door. The inlet duct is configured to extend from the auxiliary power unit to the aircraft housing and has a sidewall that defines a flow passage through which APU noise propagates. The actuator is disposed at least partially within the inlet duct. The door coupled to the actuator. The actuator is also configured to selectively rotate the door between at least a first position, in which at least a portion of the door deflects APU noise in a first direction, and a second position, in which at least a portion of the door deflects the APU noise in a second direction.