Engine Order Cancelation in a super sports car cabin

Abstract

Active noise control (ANC) has been used in several systems to improve acoustic performance while avoiding increases in the size and weight required by passive noise control solutions. This paper considers an ANC application aimed at controlling the sound field in the cabin of a supersports car with a naturally aspirated engine. This work studies the performance of a system that employs microphones and loudspeakers in the car cabin and uses a reference signal obtained from CANbus data. The controller exploits a multichannel, multi-order Fx-LMS algorithm to control the sound only in the region surrounding the driver's ears. Due to the nature of the car, this ANC application provides an interesting and challenging case study due to the rapidly changing acoustic excitation provided by the engine. The paper therefore describes a system for noise reduction, focusing on engine order reduction, aiming at achieving control during the most representative manoeuvre known as the "Wide-Open Throttle" (WOT). The investigated controller - acting locally and only on some orders simultaneously - shows good sound attenuation over the entire spectrum, with peaks of reduction exceeding 10 dB, and achieving a 5% overall decrease in the loudness, which is calculated according to ISO 532-1.