The importance of loudspeakers in car audio system is more prominent. In order to show excellent timbre and positioning sense, the number of speakers and its layout are very important conditions. Speaker and effect: in the field of car audio, people have been pursuing such an effect: sitting in the car is like sitting in front of the stage, all the sounds are emitted from the front windshield. Closing your eyes is like feeling at the scene of a concert. The sound of each instrument can achieve the best replay effect. This is what we usually call professional hi fi (high fidelity) effect.