Real Time Active Noise Control of Engine Booming in Passenger Vehicles 2007-01-0411
While driving, the low frequency interior noise below 200Hz causes the main component that irritates the auditory acoustic sense. In order to remove this low frequency noise, passive noise control methods were used such as application of sound absorbing material or isolation of noise source. These methods bring out increment in cost and weight of the vehicle and result in poor fuel efficiency. Recently, various Active Noise Control (ANC) methods to suppress the low frequency noise began to launch into application. Nissan developed the Single Input, Single Output (SISO) Active Noise Control system and applied it to their passenger vehicle, Blue Bird and Plymouth Prowler (Dodge) was equipped with Active Exhaust Noise Control System mitigating the back pressure inside the muffler. Also, demand for the Active Silencer System is being increased for the emergency vehicles. Main obstacle for the ANC system is cost effectiveness problem. But as long as the demand for the ride comfort is increased, the demand for the ANC system will grow gradually. In this paper, an ANC system for passenger vehicles to cancel the engine booming noise is implemented using DSP based control unit including four microphones and two actuators (speakers). A feed-forward control method called Multiple Error Filtered X- Least Mean Square (MEFX-LMS) algorithm is used and the space between speakers and microphones is modeled as an FIR filter. This system has been implemented on a passenger car and noise reduction at driver and passenger seats are presented. The results of this study show 10 dB reduction in engine booming noise in 2000-3000 rpm of engine speed, which is the cruise range of most cars.