Kyoichi Watanabe

Sound absorption structure

A sound absorption structure which is mainly applied to an intake system of an automotive engine for suppressing noise level. The sound absorption structure comprises a base duct portion, and an extended duct portion in which a sound absorption material is installed, and a Helmholtz resonator. The extended duct portion is formed such that a representative diameter of the extended duct portion is greater than that of the base duct portion while connected to the base duct portion. The Helmholtz resonator is set to be resonant at a frequency corresponding to a frequency range of a resonance generated by the installation of the extended duct portion including the sound absorption material. The Helmholtz resonator is integrally formed with the extended duct portion. Therefore, the sound absorption structure ensures an excellent sound absorption ability in the whole frequency range.

Development of high-performance all-polyester sound-absorbing materials

This paper describes two kinds of newly developed polyester sound-absorbing materials. One mainly consists of modified cross-section polyester fabric, and the other consists of recycled polyester fabric. They provide noticeably higher sound-absorbing performance than traditional materials like shoddy or urethane foam. This is because the new materials have greater surface area than that of traditional materials at an identical weight. Another feature of the new materials is their excellent recyclability since they are made of polyster. Application of the new materials to the dash silencer and floor carpeting resulted in a significant improvement in sound insulation performance while achieving weight savings.