The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 29, 1977
Filed:
Sep. 15, 1975
John M Epley, Portland, OR (US);
Hearing Evaluation & Acoustic Research, Inc., Portland, OR (US);
Abstract
A method for rapidly and accurately measuring the acoustical attenuation effectiveness of various personal hearing protection devices as worn, particularly in-the-ear type protectors under conditions of normal fit in a working environment having significant ambient noise. The method comprises presenting an audio signal to an ear both with and without the hearing protector in place and noting the difference in intensity of the applied signal, measured in decibels, required to obtain the same perceived amplitude level in each case. The perceived amplitude level may be either the threshold of the subject's hearing perception or a supra-threshold reference point determined by a comparison of the test ear signal with a reference signal in the contralateral ear to allow for testing in ambient noise levels of high or fluctuating intensity. The test signal is preferably a multi-frequency complex signal having a preweighted power spectrum which emphasizes those frequencies which are particularly hazardous. The preferred supra-threshold test utilizes a reference signal in the non-test ear which is audibly distinguishable from the signals applied to the test ear other than with respect to amplitude.