Possibilities and Benefits of Active Noise Control (ANC) in Truck Cabins

A truck engine excites the periodic noise components inside the truck cabin. Those harmonic noise components are related to the engine rotational speed. The noise component directly related to this speed is called the 1st order. 2nd order is 2 times this frequency, 3rd order 3 times, and so on. Also half-orders, such as 2.5 and 3.5 exist. The sound pressure level of each order varies as a function of the engine speed and the location in a cabin. The conventional noise diminishing and treatment measures rarely affect the orders directly but only certain frequency ranges. To affect individual orders Active Noise Control (ANC) may be used. ANC system is able to produce noise-cancelling anti-orders, which are locked to the engine speed. Such system has been simulated in this study using noise data measured in a truck cabin. The truck is manufactured by Dongfeng Motor Company Ltd. (DFL). The data has been treated in the simulation process with a model of the control system. The end result may be evaluated both numerically and by listening tests. The possible benefits of the proposed ANC system include less fatigue to driver and co-driver, no need for excessive noise insulation in the truck and more comfortable driving conditions. The challenges in designing the system are its complexity, reliability, and potentially high price. These pros and cons are discussed in the paper and a concept of the system realization is given