A Road Noise Cancellation (RNC) system is an Active Noise Cancellation (ANC) system implemented in a vehicle in order to minimize undesirable road noise inside the passenger cabin. Current RNC systems undesirably affect the frequency response of music playback. The RNC system's error microphones sense all the sound in the passenger cabin, including the music. Hence, RNC systems will cancel this total sensed sound, and not only the road induced noise. A new True Audio algorithm can directly remove the music signal from the error microphone signals and leave only the interior noise portion. In order to correctly estimate the music portion at the error microphones, True Audio implements a novel control topology based on a new multiple channel, real time modeling of the music's secondary path transfer function. To validate the effectiveness of the proposed algorithm, experimental and numerical simulations were performed. The numerical studies use logs of real sensors mounted on a vehicle forming an RNC system with six reference accelerometers, five control speakers and six error microphones. Both the models and measurements show that the True Audio algorithm preserves the frequency response of music when the RNC system is activated.
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