Knock detection in automobile engines

Although advances in the precise estimation of knock energy are partly due to advances in signal processing, car manufacturers have not ceased their efforts to improve knock detection. Improving the engine performance usually reduces pollution rates by a few percent. By studying the physical phenomena that cause knock, we may further reduce pollution rates. No method, however, is able to replace the human ear in distinguishing between heavy knock and mechanical shocks. Perhaps new acoustic sensors will bring a significant improvement in knock detection.