Name: ASA S12.42 PDF - Engineering Standards Download
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ASA S12.42 – American National Standard for Methods for the Measurement of Insertion Loss of Hearing Protection Devices in Continuous or Impulsive Noise Using Microphone-in-Real-Ear or Acoustic Test Fixture Procedures.

This standard specifies microphone-in-real-ear (MIRE) methods for the measurement of the insertionloss of active and passive circumaural earmuffs, helmets, and communications headsets, andspecifies acoustic test fixture (ATF) methods for the measurement of the insertion loss of active andpassive earplugs, earmuffs, helmets, and communications headsets. The MIRE methods areappropriate for use with continuous noise whereas the ATF methods may be used with bothcontinuous noise and high-level impulsive noise test signals. The standard contains information oninstrumentation, calibration, and electroacoustic requirements, procedures for determining soundpressure levels in the ear with and without the hearing protection devices in place, and procedures forcalculating the corresponding insertion loss values. The standard also describes how to combine theactive contribution of insertion loss for active devices measured using the MIRE method with thepassive real-ear attenuation measured in accordance with ANSI/ASA S12.6 to obtain an attenuationvalue for use in estimating sound pressure levels for active protectors in accordance with ANSI/ASAS12.68. Requirements for reporting of the data are also described.