Patents Assigned to Park Trading Co., Ltd.
  • Sound wave attenuation device
    Patent number: 4540063
    Abstract: A sound attenuation device is disclosed which is capable of simultaneously attenuating sound waves of both high and low frequencies bands while leaving other frequencies undisturbed. The device is comprised of an outer shell having inlet and outlet apertures at its opposite ends and containing a pair of sound absorbing plates having a pair of thin sheets of a fabric of substantial air permeability and elasticity disposed therebetween and forming an air chamber between the sheets.
    Type: Grant
    Filed: July 27, 1984
    Date of Patent: September 10, 1985
    Assignee: Park Trading Co., Ltd.
    Inventors: Akira Ochi, Toshihiko Asada