Automotive applications of a hybrid active noise and vibration control

Fuel economy, as well as social-economical factors in Europe, Asia and other market places for automotive vehicles have forced manufacturers to design smaller and lighter vehicles. Some manufacturers have plans and designs to introduce even smaller and lighter vehicles in the late 1990s and the beginning of the next century. Lighter vehicles are typically more susceptible to noise and vibrations. Furthermore, as vehicles age, their vibration and noise levels increase. In parallel, there have been efforts in using different noise control techniques for quieting small aircraft. Today, noise and vibration control have become a prime consideration in the general manufacturing industry, and more specifically the aircraft and automotive industries. Increased attention to product quality has brought the issue of "psycho-acoustics" to the transportation industry. Automotive manufacturers believe that noise and vibration levels in a vehicle are measures of quality used by the consumer. Thus within recent years, there has been a major increase of effort in the design of noise and vibration characteristics of vehicles that would better appeal to the occupants. This paper presents some results from their research and development in the area of active/adaptive noise control in transportation systems with specific results from their activities related to aircraft and to automotive vehicles.