GRAS 45CA Headphone/Hearing-protector Test Fixture

Introduction

GRAS 45CA provides the basis for reliable and exact measurements and is designed with

• A test fixture mounted on a resilient base that reduces the noise floor to a minimum in a typical test situation. Foam plugs and grease are supplied to avoid sound leakage along the cable
• A test fixture head, made for optimizing the acoustic isolation
• An acoustic cup and plug for testing the acoustic isolation
• A range of molded-rubber KEMAR pinnae, e.g. for testing earplugs, can be fitted

The 45CA’s robust design is ideally suited for binaural testing of active and passive earplugs, as well as circumaural hearing protectors.

It is primarily intended for testing the performance of hearing-protection devices such as earplugs and earmuffs (supra-aural and circum-aural) but can also be used for testing sound sources such as earphones and headphones. It is fitted with either microphones or ear simulators, depending on the device to test and the standard to comply with.

Compliance with ISO 4869-3, IEC 60318-1, and IEC 60318-4 assures technicians, decision-makers, and authorities of repeatability and transparent data when developing and verifying hearing protectors.

The pinnae for the 45CA are the same as the standardized KEMAR pinnae but rounded to fit the large 45CA base plate. This large base plate reduces or eliminates the risk of leakage.

The 45CA includes two plugs for measuring the acoustic isolation in a closed ear.

We recommend calibration before each use to ensure the accuracy of your measurements. The GRAS 42AP Intelligent Pistonphone or the GRAS 42AA Pistonphone are ideally suited for this task.

Configurations for typical applications and use

45CA Headphone/Hearing-protector Test Fixture, Non-configured is a versatile test platform that you can configure to suit specific needs. The most common configurations can be ordered fully assembled, calibrated and tested from GRAS These are:

45CA-1 Headphone/Hearing-protector Test Fixture, ISO 4869-3 1″ Mic. LEMO

The 45CA-1 is a configuration for testing outside-the-ear devices, i.e. for measuring the insertion loss of earmuffs and the sound quality of headphones. In this configuration, 45CA is configured with two GRAS 40EN 1″ pressure microphones. The configuration complies with ISO 4869-3.

45CA-2 Headphone/Hearing-protector Test Fixture, ISO 4869-3 1/2″ Mic. CCP

The 45CA-2 is a configuration for testing of outside-the-ear devices, i.e. for measuring the insertion loss of earmuffs and the sound quality of headphones. In this configuration, 45CA is configured with two GRAS 40AD 1/2″ pressure microphones. This configuration complies with ISO 4869-3

45CA-3 Headphone/Hearing-protector Test Fixture, IEC 60318-1 LEMO

45CA-3 is configured for measurement of insertion loss of circum-aural hearing protectors and the sound quality of headphones, with two RA0039 Ear Simulators with 40AG 1/2″ externally polarized microphones. The configuration complies with IEC 60318-1. The RA0039 cannot be used with a pinna simulator, and therefore cannot be used for measuring in-ear earphones.

45CA-4 Headphone/Hearing-protector Test Fixture, IEC 60318-1 CCP

The 45CA-4 is configured with two RA0039 Ear Simulators with 40AO 1/2″ prepolarized microphones. The configuration complies with IEC 60318-1 and is used for measurements of insertion loss of circum-aural hearing protectors and sound quality of headphones. The RA0039 cannot be used with a pinna simulator, and therefore cannot be used for measuring in-ear earphones.

45CA-5 Headphone/Hearing-protector Test Fixture, IEC 60318-4 LEMO

The 45CA-5 is configured with RA0045 externally polarized ear simulators for use with pinna simulators. It can be used for measurements of the insertion loss of earmuffs and earplugs, and the sound quality of earphones and headphones. The configuration complies with IEC 60318-4.

45CA-6 Headphone/Hearing-protector Test Fixture, IEC 60318-4 CCP

The 45CA-6 is configured with RA0045-S1 prepolarized ear simulators for use with pinna simulators. This configuration can be used for measurements of the insertion loss of earmuffs, sound quality of earphones and hearing aids. The configuration complies with IEC 60318-4.

45CA-7 Headphone/Hearing-protector Test Fixture, IEC 60318-4 LEMO, with Anthropometric Pinnae

The 45CA-7 is configured with RA0045 externally polarized ear simulators and anthropometric pinnae. It can be used for measurements of the insertion loss of earmuffs and earplugs, and the sound quality of earphones and headphones. The configuration complies with IEC 60318-4.

45CA-8 Headphone/Hearing-protector Test Fixture, IEC 60318-4 CCP, with Anthropometric Pinnae

The 45CA-8 is configured with RA0045-S1 prepolarized ear simulators and anthropometric pinnae. This configuration can be used for measurements of the insertion loss of earmuffs, sound quality of earphones and hearing aids. The configuration complies with IEC 60318-4.

45CA-9 Headphone/Hearing-protector Test Fixture, High-Frequency Ear Simulator, and  Anthropometric Pinnae, LEMO

The 45CA-9 is configured with RA0401 externally polarized high-frequency ear simulators and anthropometric pinnae. It can be used for measurements of hearing aids, earphones, and headphones up to 20 kHz. The configuration complies with IEC 60318-4.

45CA-10 Headphone/Hearing-protector Test Fixture, High-Frequency Ear Simulator and  Anthropometric Pinnae, CCP

The 45CA-10 is configured with RA0402 prepolarized ear simulators and anthropometric pinnae. It can be used for measurements of hearing aids, earphones, and headphones up to 20 kHz. The configuration complies with IEC 60318-4.

45CA-11 Headphone/Hearing-protector Test Fixture, Hi-Res Ear Simulator and  Anthropometric Pinnae, LEMO

The 45CA-11 is configured with RA0403 externally polarized hi-res ear simulators and anthropometric pinnae. It can be used for measurements of hearing aids, earphones and headphones up to 50 kHz. The configuration is compatible with IEC 60318-4.

45CA-12 Headphone/Hearing-protector Test Fixture, Hi-Res Ear Simulator and  Anthropometric Pinnae, CCP

The 45CA-12 is configured with RA0404 prepolarized hi-res ear simulators and anthropometric pinnae. It can be used for measurements of hearing aids, earphones, and headphones up to 50 kHz. The configuration compatible with IEC 60318-4.

The application-specific items for each of these configurations are listed under the tab Ordering Information.

System verification

For daily verification and check of your measurement setup, we recommend using a calibrator like GRAS 42AG Multifunction Sound Calibrator. For proper sensitivity calibration, we recommend using a pistonphone like GRAS 42AP Intelligent Pistonphone.

Service

If you accidentally damage the Ear Simulator, we can—in most cases—replace and repair it at a very reasonable cost and with short turn-around time. This not only protects your investment but also pleases your quality assurance department because you don’t have to worry about new serial numbers, etc.

Calibration

Before leaving the factory, all products are calibrated in a controlled laboratory environment using traceable calibration equipment. Depending on the use, measurement environment, and internal quality control programs, we recommend recalibrating the system at least once a year.

Performance and warranty

The GRAS 45CA is made of components from our standard portfolio and are all manufactured of high-quality material and branded parts that were chosen and processed to ensure life-long stability and robustness. This enables us to offer 5 years warranty against defective materials and workmanship.
Exceptions: The warranty period for cables is 6 months.