45CB Acoustic Test FixtureG.R.A.S. Sound & Vibration (G.R.A.S.) has announced the North American market introduction of the G.R.A.S. 45CB Acoustic Test Fixture According to ANSI S12.42.

Offering high-reliability performance over a wide dynamic range, the 45CB is expressly designed to meet a growing industry need for commercially available acoustic test fixtures (ATF) that can help meet or exceed the ANSI/ASA S12.42 standard, “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.”

The 45CB provides sufficient acoustic damping for objective measurements of both high-level continuous impulsive noise and the attenuation-related insertion loss encountered with active and passive hearing protection devices such as earplugs, earmuffs and safety helmets. The sturdy, high-temperature and humidity resistant construction of the 45CB is ideally suited for outdoor measurement environments, as well as simulated real-life conditions of test sites, vehicle interiors, aircraft and other areas. In addition, Ear Simulators with built-in ¼? pressure microphones ensure a measurement system that can rapidly and correctly account for impulse peaks produced by heavy industrial and agricul­tural equipment and guns. They can therefore be used with any type of test signal or real-life noise source, including environments where use of human test subjects is simply not possible, due to high noise levels or expressed requirements for objective statistical data.

The 45CB fulfills requirements for real-life objective hearing protection measure­ments over a wide dynamic range, including self-insertion loss measurements of greater than 70 dB over a wide frequency range. A peak dynamic level of 174 dB allows for realistic testing levels. Levels of up to 190 dB can be measured and calculated accurately based on closed ear measurements, combined with mea­surement of the transfer function of the open ear (TFOE). Ear canal extension dimensions, rubber coating and appropriate shore hardness make it possible to further measure the insertion loss of insertion plugs and other elastomeric materials at actual human body temperatures.

When testing calls for the use of continuous noise, broadband random noise is recommended, as outlined in ANSI S12.42. Measurements can also be conducted using recorded signals of the actual usage environment for intended hearing protection devices, such as vehicle noise and similar sources. When measuring with continuous noise, a variety of G.R.A.S. free-field and random incidence measurement microphones may be used for reference.

The G.R.A.S. 45CB Acoustic Test Fixture According to ANSI S12.42 includes the head assembly, heating control panel and connectors for both couplers and heating elements; two ear simulators, based on IEC 60318-4, including a G.R.A.S Type 40BP ¼” pressure microphone and newly designed ear canal extension; two calibration plugs for self-insertion loss verification; two ¼” LEMO preamplifiers with compatible 7-pin connector and lightweight cable; left and right pinnae; silicone grease; a 2.5 mm hex key; a flight case with removable wheels; and a 24V DC main adapter for heating elements.

All G.R.A.S. products are made of high-quality materials that will ensure life-long stabil­ity and robustness over their useful service life. The G.R.A.S. 45CB Acoustic Test Fixture According to ANSI S12.42 is delivered fully assembled. An individual test certificate is included with each 45CB. All G.R.A.S. products are calibrated in a controlled laboratory environment using traceable calibration equipment, with subsequent annual calibrations recommended. In addition, the G.R.A.S. 45CB Acoustic Test Fixture According to ANSI S12.42 is offered with a two-year comprehensive product warranty. For more information, visit