GRAS RA0045 Externally Polarized Ear Simulator According to IEC 60318-4 (60711)

Introduction

The RA0045 Ear Simulator is for making acoustic measurements on earphones coupled to the human ear by ear inserts such as tubes, ear moulds, or ear tips. The acoustic input impedance of RA0045 closely resembles that of the human ear and, as a result, loads a sound source in very much the same way.

The RA0045 complies with the following international requirements:

• IEC 60318-4: Occluded-ear simulator for the measurement of earphones coupled to the ear by ear inserts.
• ITU-T Recommendations P.57 (08/96) Series P: Telephone transmission quality, Objective measuringapparatus: Artificial ears.

It is measured and calibrated according to the ITU-T Recommendation P.57.

Design

The RA0045 embodies a number of carefully designed volumes connected via well-defined and precisely tuned resistive grooves. In an equivalent electrical circuit, capacitors would represent the volumes, and inductance and resistance would represent respectively air mass and air flow within the resistive groves.

It is delivered with a built-in GRAS 40AG 1/2″ externally polarized pressure microphone and an individual calibration chart for the ear simulator.

Typical Applications and Use

The RA0045 is for measurements on earphones and hearing aids coupled to the human ear by ear inserts such as tubes, ear moulds, or ear tips.

In accordance with ITU-T Recommendation P.57, it can be used with the following GRAS pinna simulators for testing telephones:

• GRAS RA0056 Low-leak Pinna Simulator
• GRAS RA0057 High-leak Pinna Simulator

It is also part of the GRAS 43AC Artificial Ear which is a complete test jig for acoustic testing of earphones coupled to the ear by inserts.

A comprehensive range of accessories for making measurements in accordance with IEC 60318-4 are available. See the tab Ordering info.

Compatibility

The RA0045 can be used with a standard LEMO preamplifier, e.g. the GRAS 26AK 1/2″ Preamplifier or the GRAS 26AC 1/4″ Preamplifier fitted with an adapter. For the 1/4″ preamplifier, use either the straight RA0003 Adapter or the right-angled RA0001 Adapter.