GRAS 43AC Ear Simulator Kit Instruction Manual

GRAS 43AC Ear Simulator Kit

Product Information

The GRAS 43AC Ear Simulator Kit is a test jig designed for measurements on hearing aids and insert-type earphones. It includes an ear simulator, preamplifier, and various accessories. The kit is compatible with externally polarized configurations (43AC, 43AC-S4 to 43AC-S6) and prepolarized configurations (43AC-S1, 43AC-S5, and 43AC-S7). The ear simulator is compliant with IEC 60318-4 standards and is available in both LEMO and CCP connectors. The kit also supports TEDS functionality for reading and writing data like properties and calibration data if your measurement platform supports it.

Product Usage Instructions

Assembling the Test Jig:
Follow the steps below to assemble the 43AC Ear Simulator Kit:

1. Slacken the grub screw and move the slider up or down to adjust the spring force. An Allen key is provided for this purpose.
2. Attach the RA0001 Angled Adapter to the ear simulator using finger force only. Do not use the preamplifier as a lever.

Delivered Items:
The 43AC Ear Simulator Kit includes the following items:

• Test Jig RA0052
• Test Jig with spring-loaded clamp (not used in 43AC)
• Ear Simulator (RA0045 for externally polarized configurations or RA0045-S1 for prepolarized configurations)
• Preamplifier (26AC with integrated cable)
• Accessories: GR0408 External Ear Canal Union Nut, GR0409 Nylon cord (1 meter), MI0070 Optional Items

Optional Items (not included):
For specific applications, the following optional items can be used:

• GR0435 In-ear Adapter
• GR0436 Tube Stud
• GR0438 Ear-mould Simulator
• GR0440 Tube Stud
• GR0433 Calibration Adapter
• GR0434 Stop Washer

TEDS Compatibility:
If your measurement platform supports Transducer Electronic Data Sheets (TEDS), the ear simulator kits with constant-current power microphone components (-S1, -S5, and -S7 configurations) are IEEE 1451.4 TEDS v. 1.0 compliant. This allows you to read and write data like properties and calibration data

Introduction

The 43AC Ear Simulator Kit is a test jig for measurements on hearing aids and insert-type earphones. Ear simulator, preamplifier and accessories are included.

Fig. 1:  Assembled 43AC Ear Simulator Kit

Delivered Items

Test Jig
RA0052| Test Jig with a spring-loaded clamp
Externally Polarized Configurations
 | Ear Simulator| Preamplifier
43AC| RA0045 Ear Simulator According to IEC 60318-4, LEMO| 26AC(integrated cable)
43AC-S4| RA0401 High-Frequency Ear Simulator, LEMO| 26AC(integrated cable)
43AC-S6| RA0403 Hi-Res Ear Simulator, LEMO| 26AC(integrated cable)
Prepolarized Configurations
43AC-S1| RA0045-S1 Ear Simulator According to IEC 60318-4, CCP| 26CB
43AC-S5| RA0402 High-Frequency Ear Simulator, CCP| 26CB
43AC-S7| RA0404 Hi-Res Ear Simulator, CCP| 26CB
Accessories
GR0408| External Ear Canal
GR0409| Union Nut
MI0070| Nylon cord, 1 meter
Optional Items—not included

For hearing aids using tube inserts or placed in the ear (See Fig. 3)
GR0435| In-ear Adapter
GR0436| Tube Stud
GR0438| Ear-mould Simulator
GR0440| Tube Stud
For calibration
GR0433| Calibration Adapter
GR0434| Stop Washer

TEDS Compatibility
Ear simulator kits with constant-current power (CCP)microphone components (configurations -S1, -S5, and -S7) are IEEE 1451.4 TEDS v. 1.0 compliant. If your measurement platform supports Transducer Electronic Data Sheets (TEDS), you will be able to read and write data like properties and calibration data.

Assembly

Assembling the Test Jig
The exploded view below shows how the 43AC is assembled. When attaching the RA0001 Angled Adapter to the ear simulator, take care to use finger force only – do not use the preamplifier as a lever.

Fig. 2 : Exploded view of the user-serviceable components of the 43AC Ear Simulator Kit

Note: The spring-loaded arm is part of RA0052 Test Jig as delivered, but in 43AC it is normally not used to hold the DUT when testing ITE and BTE transducers, so it can therefore be ignored.

Assembling Accessories for Testing ITE and BTE Transducers
Below is shown how the accessories for measuring on in-the-ear (ITE) and behind-the-ear (BTE) hearing aids are mounted onto the ear simulator

Fig. 3:  Assembled and exploded views of the ear simulator itemizing user-serviceable accessories for testing earphones either coupled to the ear via tube inserts or placed in the ear

Calibration

Level Calibration
This paragraph describes level calibration. How to perform a frequency calibration is described on page 8. In the following, a pistonphone is used, the procedure when using a sound calibrator is the same. However, do note that the corrections factors differ.

Correction Factors
The correction factors for calibration with a 42AP/42AA Pistonphone or a 42AG Multifunction Calibrator are listed below. These correction factors are needed to account for the effective volume resulting from using a pistonphone or the 42AG Multifunction Sound Calibrator.

Correction factors

 | External Ear Canal| Correction factor
42AP and 42AA| GR0408| -1.03 dB
42AG @250 Hz, 114 dB| GR0408| -0.09 dB
42AG @250 Hz, 94 dB| GR0408| -0.09 dB
42AG @1KHz, 114 dB| GR0408| -0.2 dB
42AG @1KHz, 94 dB| GR0408| -0.2 dB

Fig. 4. Correction factors for 42AA/AP Pistonphone and 42AG Multifunction Sound Calibrator Se the following section Calibration at 1 kHz

Calibration at 1 kHz
At 1 kHz, the frequency response changes from unit to unit. The actual value for the specific ear simulator is stated on the calibration chart and must be added to the correction. For example: If the response of the specific ear simulator at 1 kHz is + 1.45 dB (re 500 Hz), the final correction value will be -0.2 + 1.45 = 1.25 dB. GRAS recommends calibrating at 250 Hz whenever possible.

Procedure
Before calibration, mount the external ear canal as shown below.

Fig. 5: Ear simulator ready for level calibration, with External Ear Canal and Union Nut.

Important: Do not extract the microphone housed in the ear simulator since this would invalidate the factory calibration. You will be calibrating the ear simulator as a whole with a pistonphone or sound calibrator fitted with a ½” coupler. This, in effect, increases the coupler volume such that the signal will be reduced. Therefore, the correction factors listed in Fig. 4 on page 7 must be used.

Pistonphone
The procedure listed below is for using a pistonphone.

1. Snap the spring-loaded clamp (see 1) to its upright position, or remove it.

2. Unscrew the collar of the pistonphone and remove the O-ring (see 6).
   Fig. 6: Level calibration using a pistonphone

3. Place the coupler of the pistonphone over the ear simulator and push it gently down to the stop and switch on.

4. Set the analyzer to either wideband or to the ⅓ octave band whose center frequency is 250

5. When conditions are stable, adjust the analyzer so that it correctly gauges the calibration signall (nominally e.g 114 dB, corrected with the correction factor). See the pistonphone manual for making barometric

6. Switch the Pistonphone off and remove it from the ear

Multifunction Sound Calibrator
The 42AG fits directly onto the ear simulator. It automatically corrects for ambient calibration conditions. The correction factor is listed in Fig. 4 on page 7.

Frequency Calibration
This section describes how to perform a frequency calibration using a 40BP ¼” Microphone as sound source. Fig. 7 shows how to configure the coupler for calibration using the accessories provided, and Fig. 8 shows how these should be used with:

• 40BP ¼” Microphone
• RA0086 Transmitter Adapter

Fig. 7: Assembled and exploded views of the coupler itemizing user- serviceable accessories for individual calibration

The ¼” microphone is used as a high-impedance sound source. The complete set- up is shown in Fig. 9 on page 10. The computer is capable of concurrently generating and measuring audio frequency signals. The 14AA Actuator Supply receives a swept tone generated by the computer and sends this to the coupler mounted in the jig, also shown in Fig. 9. The coupler picks up the resulting audio signal and sends this back to the computer which traces out and displays the coupler response. An example of a displayed response is shown in Fig. 10.

Fig. 8: Assembled and exploded views showing how the GR0434 is used when calibrating the ear simulator. 40BP and RA0086 are available from GRAS.

Fig. 9: Block diagram of a complete set-up for calibration

Fig. 10: Example of a calibration result using a swept tone

Warranty, Service and Repair

Calibration

• Before leaving the factory, all GRAS products are calibrated in a controlled laboratory environment using traceable calibration equipment.
• We recommend a yearly recalibration at minimum, depending on the use, measurement environment, and internal quality control programs.
• We recommend calibration prior to each use to ensure the accuracy of your measurements.

Warranty
Damaged diaphragms in microphones can be replaced. The microphone diaphragm, body, and improved protection grid are made of high-grade stainless steel, which makes the microphone resistant to physical damage, as well as corrosion caused by aggressive air or gasses. This, com- bined with the reinforced gold-plated microphone terminal which guarantees a highly reliable connection,enables GRAS to offer 5 years warranty against defective materials and workmanship.

The warranty does not cover products that are damaged due to negligent use, an incorrect power supply, or an incorrect connection to the equipment.

Service and Repairs
All repairs are made at GRAS International Support Center located in Denmark. Our Support Center is equipped with the newest test equipment and staffed with dedicated and highly skilled engineers. Upon request, we make cost estimates based on fixed repair categories. If a product covered by warranty is sent for service, it is repaired free of charge, unless the damage is the result of negligent use or other violations of the warranty. All repairs are delivered with a service report, as well as an updated calibration chart.

Manufactured to conform with:

• CE marking directive: 93/68/EEC
• WEEE directive: 2002/96/EC
• RoHS directive: 2002/95/EC

GRAS Sound & Vibration continually strives to improve the quality of our products for our customers; therefore, the specifications and accessories are subject to change.

Revision History

Copyright Notice © 2005-22 GRAS Sound & Vibration www.GRASacoustics.com
Any technical documentation that is made available by GRAS is the copyrighted work of GRAS and is owned by GRAS. The content in this document is subject to change without notice. GRAS Sound & Vibration is not liable or responsible for any errors or inaccuracies that may appear in this document.

Trademarks
Any other product names mentioned in this document may be trademarks or registered trademarks of their respective companies and are hereby acknowledged.

References

• GRAS Sound and Vibration

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