Car designers are reducing vehicle weight, often by using less noise-dampening insulation in the car's interior. Using lighter materials inside, can however increases perceptible road noise inside the vehicle, which then penetrates the interior (and passenger ears).
Traditional NVH (Noise, Vibration, and Harshness) methods have difficulties in counteracting the above mentioned issues satisfactorily, and therefore these technologies also tend to add weight, which cancels out the fuel economy effect of using lighter materials.
Road Noise Cancellation (RNC) which detects and diminishes unwanted road noise, and thereby improves vehicle weight and handling without impacting interior noise levels is increasingly being used as antisound philosophy.