Externally Polarized Ear Simulator Based on IEC 60318-4 GRAS RA0045-S5

Introduction

• The RA0045-S5 Externally Polarized Ear Simulator is a special type of ear simulator for making high level acoustic measurements on earphones coupled to the human ear by ear inserts such as tubes, ear moulds, or ear tips. It has an input impedance closely resembling that of an average human ear, and, as a result, loads a sound source in very much the same way.

It is based on 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.

Design

• The RA0045-S5 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 40BP 1/4″ Ext. Polarized Pressure Microphone and an individual calibration chart for the ear simulator.

Typical Applications and Use

• The RA0045-S5 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
• A comprehensive range of accessories for making measurements in accordance with IEC 60318-4 are available. See the tab Ordering info.

Compatibility

• RA0045-S5 can be used with a standard 1/4″ preamplifier, e.g. GRAS 26AC-1 1/4″ Standard Preamplifier with 3 m Integrated Cable.