Performance of New Acoustical Test Fixtures Complying with ANSI S12.42-2010, With Particular Attention to the Specification of Self Insertion Loss

摘要

ANSI/ASA S12.42-2010 specifies how to measure the insertion loss of hearing protectionrndevices (HPDs). It requires use of acoustical test fixtures (ATFs) that are similar to existingrnATFs but differ in terms of the earcanal length, inclusion of a simulated flesh lining thernearcanal, and a heater to bring the fixtures to approximate body temperature. Thesernfeatures were necessary for the devices to provide insertion loss data with betterrncorrespondence to measurements on human heads. This was important as use of an ATF isrnthe standard’s preferred method for tests on certain electronic earplugs and for all impulserntesting. At least two ATFs [one from G.R.A.S. Sound and Vibration and the other from thernInstitute of St. Louis (ISL)] are intended to comply with the standard. The studiesrnreported herein are part of an ongoing evaluation of these heads in which ATF insertionlossrnmeasurements for a sample of passive earplugs and earmuffs are compared to real-earrnattenuation at threshold data per ANSI S3.19-1974. This study will include discussion ofrnrecent modifications to one of those heads intended to address issues that were reported inrnan initial evaluation that was previously presented [Berger, Kieper, and Stergar (2011). J.rnAcoust. Soc. Am. 130(4) Pt. 2, p. 2434].