Improvement of Car Interior Noise by Utilizing a Porous Intake Duct: Treatment Effect on an Intake System

A porous intake duct recently used as a countermeasure to reduce high frequency contents of intake duct noise reduces sharpness of the sound and has a good effect for the improvement of sound quality of car interior noise. On the other hand, by introducing a porous intake duct system, the low frequency contents of sound sometimes dominate and it makes us feel the sound as booming. So, in order to avoid this unwanted situation, to make the balance between the low and high frequency contents of the intake duct noise properly is important for achieving good sound quality. This paper describes the experimental results of how to deal with this problem.