A lot of people bought new car to come back,can undertake to new car dress up one time,besides the car high-quality goods such as cushion,ground glue,perfume,still have is engine sound insulation cotton.Can an extra piece of engine-proof cotton really improve interior noise?Different people have different opinions.In fact,now many of the original factory has equipment,for the original factory is not equipped with sound insulation cotton model,do you want to add?How useful is it in practice?In response to these questions,the truth man will,as always,through the actual measurement to tell you the answer.