Michael & Associates, Inc.
Michael & Associates, Inc.
Testing Services
Michael & Associates is accredited by the National Institute of Standards and Technology (NIST) National Voluntary Laboratory Accreditation Program (NVLAP) for tests performed according to ANSI S3.19-1974, ANSI S12.6-2016, AS/NZ S1270:2002, ANSI S12.42-2010 and EN 352:2020 parts 1-10. These accreditation criteria encompass the requirements of international standards ISO 17025.
-
ANSI S3.19-1974
According to Environmental Protection Agency (EPA) regulations, ANSI S3.19-1974 is the current testing requirement for hearing protective device labeling. 10 human subjects are required for hearing protector evaluations using 9 test freqiencies. The Noise Reduction Rating (NRR) is calculated from these data. Exact labeling requirements can be seen at:
-
ANSI S12.6-2016
ANSI S12.6-2016 is the most recent US standard that describes a method of evaluating hearing protective devices. 20 human subjects are required for insert-type hearing protectors, cap-mounted muffs and semi-aural devices. 10 human subjects are required for other types of muff-type devices and for helmets. 7 test frequencies are used. The Noise Reduction Statistic (NRS) is then typically calculated from these data. ANSI S12.68-2007 describes a rating system that requires ANSI S12.6-2016 data for rating calculations.
-
AS/NZ S1270:2002
AS/NZ S1270:2002 is the Australian test standard for hearing protective devices. The AUS standard describes a test that is similar to ANSI S12.6-2008 Method B, requiring the use of inexperienced test subjects. The goal of testing inexperienced subjects is to more accurately estimate the field attenuation provided by HPDs on end-users, as opposed to the attenuation provided to skilled and motivated laboratory subjects. 20 subjects are required for insert-type hearing protectors and 16 subjects are required for muff-type hearing protectors.
-
EN 352 Parts 1-10
EN 352-1:2020 General Requirements for Ear muffs
EN 352-2:2020 General Requirements for Ear plugs
EN 352-3:2020 General Requirements for Cap-mounted ear muffs
EN 352-4:2020 Level dependent ear muffs
EN 352-5:2020 Active noise control ear muffs
EN 352-6:2020 Ear muffs with an audio input
EN 352-7:2020 Level dependent ear plugs
EN 352-8:2020 Entertainment ear muffs
EN352-9:2020 Earplugs with an Electrical Audio Input
EN352-10:2020 Entertainment Audio Earplugs
ANSI S12.42-2010
ANSI S12.42-2010 describes a method of measuring hearing protector attenuation on 1) human heads, with microphones mounted at the entrance of the ear canal, and 2) a test fixture, with microphones mounted at the tympanic membrane location on the fixture. Michael & Associates uses the GRAS Type 45CB ANSI Acoustic Test Fixture. The Type 45CB ANSI Acoustic Test Fixture is intended for testing the performance of hearing-protection devices such as ear plugs and ear muffs (supra-aural and circum-aural). The 45CB ANSI Acoustic Test Fixture meets the requirements of ANSI Standard S12.42-2010.
Hearing protector impulse response measurements is performed according to ANSI S12.42-2010. A shock tube, manufactured by Mark Cauble of BC Precision Machine, Greendale, IN is used to generate impulses from 130 to 170 dB. Analysis of the waveform recordings is performed using the Viacoustics Trident software package and an additional Viacoustics custom software package.