G.R.A.S. RA0045-S1 Prepolarized Ear Simulator According to IEC 60318-4 (60711)

Volume: 1260 mm³ @ 500 Hz
Dyn range: 25 dB(A) to 150 dB
IEC: 60318-4


The RA0045-S1 Prepolarized 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-S1 closely resembles that of the human ear and, as a result, loads a sound source in very much the same way.

The RA0045-S1 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.


The RA0045-S1 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 G.R.A.S. 40AO 1/2" prepolarized pressure microphone and an individual calibration chart for the ear simulator.

Typical Applications and Use

The RA0045-S1 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 G.R.A.S. pinna simulators for testing telephones:

It is also part of the G.R.A.S. 43AC-S1 Artificial Ear.

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


The RA0045-S1 can be used with a standard CCP preamplifier, e.g. the G.R.A.S. 26CA 1/2" Preamplifier or the G.R.A.S. 26CB 1/4" Preamplifier fitted with an adapter. For the 1/4" preamplifier, use either the straight RA0003 Adapter or the right-angled RA0001 Adapter.

Theoretical dynamic range lower limit with G.R.A.S. preamplifier dB(A) 25
Dynamic range upper limit with G.R.A.S. CCP preamplifier dB 150
Resonance frequency kHz 13.5
Coupler volume 1260 @ 500 Hz
Temperature range, operation °C / °F -30 to 60 / -22 to 140
Temperature coefficient @250 Hz dB/°C / dB/°F 0.05
Humidity range non condensing % RH 0 to 75
IEC standard 60318-4 (former 60711)
ITU-T recommondations P.57
CE/RoHS compliant/WEEE registered Yes/Yes/Yes
Weight g / oz 52 / 1.8

Typical frequency response


 Optional items

G.R.A.S. RA0088

In Ear Adapter

G.R.A.S. GR0433

Calibration Adapter

G.R.A.S. GR0434

Stop Washer

G.R.A.S. GR0436

Tube Adapter

G.R.A.S. GR0437

Ear-mould Simulator

G.R.A.S. GR0438

Retention Ring

G.R.A.S. GR0440

Tube Adapter

G.R.A.S. RA0056

Low-leak Pinna Simulator

G.R.A.S. RA0057

High-leak Pinna Simulator

G.R.A.S. 26CA

26CA 1/2'' CCP Standard Preamplifier with BNC Connector

G.R.A.S. 26CB

26CB 1/4" CCP Standard Preamplifier with Microdot Connector

G.R.A.S. RA0001

Right-angled Adapter for 1/2" microphone and 1/4" preamplifier

G.R.A.S. RA0003

Adapter for 1/2" microphone and 1/4" preamplifier