Adaptive Technologies Inc.

Yu Du

Michael A Vaudrey

Kenji Homma

William Richard Saunders

Jonathan M Hager

An earmuff assembly with a double-shell structure is disclosed for use with a sound-attenuating circumaural headset. The earmuff assembly comprises a cup-shaped outer shell mounted on a resilient outer sealing ring and a cup-shaped inner shell mounted on a resilient inner sealing ring. By means of the two sealing rings the outer and the inner shells are brought into abutment with the head surface around an ear of a wearer. Both shells are structurally rigid. The sound attenuation performance is maximized by isolating the inner shell from the outer shell.

Sound-attenuating earmuff having isolated double-shell structure

An earmuff assembly with a double-shell structure is disclosed for use with a sound-attenuating circumaural headset. The earmuff assembly comprises a cup-shaped outer shell mounted on a resilient outer sealing ring and a cup-shaped inner shell mounted on a resilient inner sealing ring. By means of the two sealing rings the outer and the inner shells are brought into abutment with the head surface around an ear of a wearer. Both shells are structurally rigid. The sound attenuation performance is maximized by isolating the inner shell from the outer shell. The two sealing rings are interconnected through a thin skin layer of soft compliant materials, which acts as a vibration isolating/decoupling means between the outer shell and the inner shell.

A double hearing protection system comprises a circumaural hearing protector that covers and encircles the pinnae and an earplug device that is inserted into the ear canal. The earplug portion of the system comprises a tether that is coupled to the interior of a circumaural hearing protector. The tether retracts into the earcup when both the earplug and circumaural hearing protector are worn, ensuring that the earseal against the head is not broken by the retractable tether.

Double hearing protection device

A microphone housing improves the broadband noise canceling performance of an active noise canceling microphone system while also ensuring improved speech transmission through the system. First and second microphone elements are selected each having a diameter 'd' and a thickness 't'. The two microphone elements are aligned axially with the back surfaces in contact and secured in an axially aligned cylindrical cavity within a cylindrically shaped housing. The cylindrically shaped housing has an outside diameter &#x201c;D,&#x201d; an interior cavity of diameter of &#x201c;d,&#x201d; and a height &#x201c;2t&#x201d;. The housing is exposed to an environment comprising both speech and noise. The first microphone element is adapted to receive a signal having both voice and noise components, while the second microphone element is adapted to receive a signal that is predominantly noise. A controller processes signals from the first microphone element and the second microphone element. The values of D and d are selected so to obtain a ratio of D over d between 1 and about 2.4 or a near field power difference of the first microphone signal and the second microphone signal between 8 dB and 11 dB. In the event the near field power difference is more than 11 dB, the outside diameter of the microphone housing &#x201c;D&#x201d; is reduced. In the event the near field power difference is less than 8 dB, the outside diameter of the microphone housing &#x201c;D&#x201d; is increased.

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Christiansburg, VA, United States of America

Yu Du