Method for testing acoustical attenuation of hearing protectors

DETAILED DESCRIPTION The present invention is directed to a system for measuring the acoustical attenuation effectiveness of hearing protectors, especially those adapted to be worn in the ear canal.
More particularly, the present invention comprises a system for rapidly and subjectively measuring the acoustical attenuation provided by in-the-ear type hearing protectors or earplugs as normally worn by a particular individual at or near the individual's work station and without requiring the use of a low-noise or quiet-room type environment.
As used herein, the term "earplug" is understood to include hearing protectors worn within the external acoustic meatus or ear canal as well as those worn in the concha distal to the extrance to the external ear canal.
The method of the present invention, as applied to earplugs, comprises two independent alternative tests for determining the acoustical effectiveness of earplugs under differing conditions of ambient noise: the threshold test and the supra-threshold test.
The threshold test is used to measure earplug effectiveness under no-noise or non-fluctuating noise conditions, and the supra-threshold test is used to measure earplug effectiveness in the presence of relatively high or fluctuating ambient noise.
In both tests, the earplug wearer can be tested at or near his or her work station, preferably without advance notice to ensure that a true measurement of the acoustical effectiveness of the earplug is obtained as the earplug is normally worn and not as the earplug is specially fitted by the wearer in anticipation of being tested.
The test may also be performed at the time that an earplug is initially fitted to ensure that a correct fit is obtained.
In the preferred practice of both tests as applied to earplugs, a pair of transducer-equipped earcups are placed over the ears of the subject to attenuate ambient noise and expose the test ear to a test audio signal.
The earcups are specially adapted to completely surround the ear and the adjacent sound-transmitting bone structure of the skull without contacting or otherwise disturbing the placement of the earplugs