Patent ID: 8107638

Claim:
A semi-insert hearing protector, said hearing protector comprising: an enclosure having an interior air volume of at least 7 cc and defining an initial acoustic compliance, said enclosure being defined by thin walls made from a rigid or semi-rigid material, said enclosure being secured to the head of a wearer by means of an adjustable headband; a short connecting tube extending from said enclosure for communication with the ear canal, said connecting tube being substantially narrower than said enclosure and being made from a rigid or semi-rigid material, said protector including a cuff disposed over said connecting tube, said cuff being made from a resilient material and having a cross section larger than the ear canal of a wearer to prevent said connecting tube from entering the ear canal, wherein said enclosure is entirely external relative to the ear of a wearer, said hearing protector having an acoustic impedance at a distal end of said connecting tube that is substantially smaller than the acoustic impedance at the entrance of the ear canal over a useful range of audible sound frequencies and in which said enclosure and said connecting tube interact with each other to form a Helmholtz-type resonator; and damping means for decreasing the initial acoustic compliance of said enclosure as sound frequency is increased, thereby increasing the bandwidth of the low acoustic impedance of said protector.