Frye FONIX 6500-CX Workbook

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Page 1

TESTING

FM SYSTEMS

with the FONIX 6500-CX

Hearing Aid Analyzer

(Requires software version 4.20 or above)

FRYE

FRYE ELECTRONICS, INC.

P.O. Box 23391 • Tigard, OR 97281-3391 (503) 620-2722 • (800) 547-8209 Fax: (503) 639-0128 www.frye.com • e-mail: sales@frye.com

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Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

General Fitting Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Curve Labeling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Arrangement of This Workbook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Section 1: Coupler Measurements with FM Systems

1.1 Coupler Setup in the sound chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.1.1 How to Attach the 2-cc Coupler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.1.2 Hearing Aid Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.1.3 FM System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.1.4 Environmental Microphone Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.2 Omni-directional: FM-only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.2.1 Test aid alone with typical input — EHA65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.2.2 Test FM microphone with typical input — EFM80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.2.3 Test aid alone with high-level input — EHA90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.2.4 Test FM system with high-level input — EFM90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.3 Omni-directional: FM+ENV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.3.1 Single frequency output of omni-directional hearing aid in the sound chamber . . . . . . 16

1.3.2 Single frequency output of omni-directional FM mic at 65 dB SPL . . . . . . . . . . . . . . . . . 17

1.3.3 Verify increase in signal level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1.3.4 Test aid alone with typical input — EHA65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1.3.5 Test FM+ENV microphones with typical input to FM microphone — EFE80 . . . . . . . . . 18

1.3.6 Test environmental microphone response with typical input—EEF65 . . . . . . . . . . . . . . 20

1.3.7 Test aid alone with high-level input — EHA90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.3.8 Test with FM system using a high-level input — EFE90 . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.3.9 Test environmental mic response with high-level input — EEF90 . . . . . . . . . . . . . . . . . . 23

1.4 Coupler Setup in the Sound Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

1.4.1 Hearing Aid Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

1.4.2 FM System Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1.4.3 Environmental microphones on body-worn receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1.5 Directional: Testing FM-only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

1.5.1 Test aid alone with typical input — EHA65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

1.5.2 Test FM microphone with typical input — EFM80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

1.5.3 Test aid alone with high-level input — EHA90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

1.5.4 Test FM system with high-level input — EFM90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

1.6 Directional: Testing FM+ENV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

1.6.1 Single frequency output of hearing aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

1.6.2 Single frequency output of FM mic at 65 dB SPL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

1.6.3 Verify increase in signal level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

1.6.4 Test aid with typical input — EHA65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

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1.6.5 Test FM+ENV microphones with typical input to FM microphone — EFE80 . . . . . . . . . 37

1.6.6 Test environmental mic response with typical input — EEF65 . . . . . . . . . . . . . . . . . . . . 38

1.6.7 Test aid with high-level input — EHA90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

1.6.8 Test with FM system using a high-level input — EFE90 . . . . . . . . . . . . . . . . . . . . . . . . . . 40

1.6.9 Test environmental mic response with high-level input — EEF90 . . . . . . . . . . . . . . . . . . 41

Section 2: Real-Ear Evalutation with FM Systems

2.1 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

2.1.1 Hearing Aids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

2.1.2 FM System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

2.1.3 Setup for Testing Environmental Microphones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Environmental microphones on body-worn receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Environmental microphone on a hearing aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

2.2 Testing FM-Only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

2.2.1 Test aid with typical input — RHA65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

2.2.2 Test FM system with typical input — RFM80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

2.2.3 Test aid with high-level input—RHA90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

2.2.4 Test FM system with high-level input—RFM90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

2.3 Testing FM+ENV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

2.3.1 Single frequency output of hearing aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

2.3.2 Single frequency response of FM mic at 65 dB SPL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.3.3 Verify increase in signal level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.3.4 Test aid with typical input – RHA65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

2.3.5 Test FM system with typical input – RFM80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

2.3.6 Test environmental mic with typical input—REF65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

2.3.7 Test aid with high-level input—RHA90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

2.3.8 Test FM system with high-level input—RFE90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

2.3.9 Test environmental mic with high-level input—REF90 . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Glossary: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

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Introduction

This workbook contains procedures for testing FM systems with the 6500-CX hearing aid analyzer using coupler and real-ear measurement methods. An FM system consists of two main parts: a transmitter and a receiver. The transmitter microphone can come in many different sizes and shapes, and it can be omni-directional or directional. The body-worn FM receiver can be coupled to a button earphone or interfaced with the personal hearing aid via a direct audio input boot, silhouette coil, or via a neck loop. The ear-level FM receivers are housed within the BTE aid or attached to the base of the BTE via a boot connection.

No matter the combination, all FM systems can be tested. These test procedures should be performed on an FM system at least once a year. For children under the age of 5, these procedures should be performed every six months.

As with most hearing aids, both the gain and the maximum output (SSPL) of an FM system should be adjusted to meet the listener ’s auditory requirements.

There are several issues to consider when comparing the hearing aid and FM performance.

• With FM systems, the pickup microphone is normally worn at the chest, 6-8 inches (15-20 cm) under the mouth of the talker, whereas with hearing aids, the pickup microphone is worn by the listener, typically at a minimum of 3 ft. (1 m) from the talker. This difference affects both the level and the frequency content of typical input signals. With FM systems, typical speech input levels range from 75 to 85 dB SPL, as compared with 60 to 70 dB SPL for hearing aids. With the chest-worn location of the pickup microphone, the high frequencies are relatively lower in level (about 5 dB at 5 kHz) and the low frequencies are relatively higher in level (about 5 dB at 500 Hz) as compared with directly in front of the talker’s mouth.

• The increased “vocal effort” by teachers in a classroom situation may create further changes to the speech spectrum at the input to an FM system, as compared with the speech spectrum at the input of a hearing aid (Cornelisse et al., 1991).

• FM systems often have an automatic gain control (AGC) or other nonlinear characteristic that could interact with that of the hearing aid being used to deliver the FM signal—if such a hearing aid is being used in this fashion.

• The frequency response of an FM system is often not as adjustable as that of a hearing aid, limiting the range of electroacoustic modifications available.

The procedures recommended in this chapter are based on the ASHA guidelines for fitting and monitoring FM systems (1999), available at: www.asha.org/audiology/fm_guidelines.htm.

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Testing FM Systems with FONIX FP40 Analyzers

General Fitting Protocol

For the purposes of this workbook, we will assume that the hearing aid being tested has been fitted appropriately for the client’s loss. We will adjust the FM system to the output of the hearing aid.

Goals:

• For students with mild to moderately-severe losses (<80 dB HL), the goal is to match the

output of the hearing aid and the FM system when typical input signals are used. With typical inputs, the FM output will be the same intensity as the hearing aid output.

• For students with severe to profound losses (>80 dB HL), the goal is to match the gain of

the hearing aid and the FM system when typical input signals are used. With typical input signals, the FM output will be about 10 dB more intense than the hearing aid out-

put. Testing Order: Start with 2-cc coupler tests and adjustments if possible. Follow up with real-ear verification.

If time doesn’t permit both test conditions, omit the 2-cc coupler tests. For both 2-cc coupler and real-ear tests:

1. Test the user ’s hearing aid with typical input signal levels.

2. Test the FM system with typical input signal levels, and make any necessary adjustments.

3. Test the user ’s hearing aid with high input signal levels.

4. Test the FM system with high input signal levels, and make any necessary adjustments.

Curve Labeling System

In order to efficiently record and refer to the various measurements, we have adopted a curve labeling system created by Dr. Linda Thibodeau. This system is consistent with the type of measurement made and the SPL of the test signal used.

• The first letter indicates whether it was a coupler or a real-ear measurement. – All coupler measurement labels begin with an “E” for “Electroacoustic.” – All real-ear measurement labels begin with an “R” for “Real-Ear.”

• The second and third letters indicate the type of test taken. – “HA” means a hearing aid test

– “FM” means an FM-only test – “FE” means an FM+ENV test with the signal delivered to the FM microphone – “EF” means an FM+ENV test with the signal delivered to the environmental micro-

phone

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Introduction

• The numbers at the end indicate the sound pressure level of the test signal used. Examples:

– EHA65 is the electroacoustic coupler measurement of the hearing aid with the signal

input at 65 dB SPL

– EFM80 is the electroacoustic coupler measurement of the FM microphone with the sig-

nal input at 80 dB SPL

– RFE80 is the real-ear measurement of the FM+ENV with the signal delivered to the

FM microphone at 80 dB SPL

See the Glossary for a list of all the labels and their definitions.

Arrangement of This Workbook

There are two main sections in this workbook. Section 1 describes sets of coupler measurements of FM systems. Section 2 describes corresponding sets of real-ear measurements of FM systems.

Section 1 contains four different sets of testing procedures, but you only need to follow the testing procedure suitable for the FM system being tested. Section 2 contains two different sets of testing procedures. Likewise, you only need to follow the real-ear procedures suitable for the FM system. Ideally, you should perform one set of coupler measurements and one set of real-ear measurements on each FM system.

It is assumed that you will perform the specified tests in sequential order. For instance, the instructions in Section 1.2.2, Testing the FM response with typical input, assume that you have done the steps in Section 1.2.1, Testing the hearing aid response with typical input. If it is more convenient for you to alter the testing order, just be aware that some of the key presses will change.

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Testing FM Systems with FONIX 6500-CX Analyzers

1: Coupler Measurements with FM Systems

Coupler measurements of FM systems allow you to adjust the system without needing your client present. The goal is to set the FM system controls so that the user receives the FM signal at an appropriate level with reference to the acoustic signal the user receives from his personal hearing aid.

There are four different sets of measurements described in this section. Use the set that is appropriate for the FM system setup.

If the FM receiver and hearing aid are omni-directional and will fit inside the sound chamber, and:

• The FM receiver is primarily set to receive FM-only signals, follow the procedures described in Section 1.2, Omni-directional: Testing FM-only.

• The FM receiver is primarily set to receive FM with environmental signals (FM+ENV), follow the procedures described in Section 1.3, Omni-directional: Testing

FM+ENV.

If the FM receiver or hearing aid is directional or cannot fit inside the sound chamber, and

• The FM receiver is primarily set to receive FM-only signals, follow the procedures described in Section 1.5, Directional: Testing FM-only.

• The FM receiver is primarily set to receive FM with environmental signals (FM+ENV), follow the procedures described in Section 1.6, Directional: Testing

FM+ENV.

For all procedures, the hearing aid should be set to user settings.

1.1 Coupler Setup in the sound chamber

This section describes how to attach a 2-cc coupler to the FM receiver, and how to set up an FM system for coupler measurements.

1.1.1 How to Attach the 2-cc Coupler

A variety of output devices can be used with FM systems. These include button earphones, BTE cases with microphone/earphones, BTE aids with an internal FM receiver, an external FM receiver boot, or options for coupling to the personal BTE hearing aid via direct audio inputs, silhouette coils, or neck loops. This section contains a description of how to arrange the 2-cc coupler with each type of output device.

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Section 1: Coupler Tests of FM Systems

Figure 1.1.1A Figure 1.1.1B Figure 1.1.1C

Button earphone Internal FM receiver Silhouette coil

External FM boot receiver

Direct audio input

Button earphone (Figure 1.1.1A)

1. Remove the ear-level adapter from the HA-2 coupler, if necessary.

2. Snap on the button earphone to the HA-2 coupler.

3. Place the coupler/hearing-aid assembly on a foam pad outside the text box, 2 ft. (60 cm) from the transmitter during testing.

BTE case with microphone/earphone or BTE aid with internal FM receiver, external FM boot receiver, or direct audio input (Figure 1.1.1B)

1. Attach the ear-level adapter to the HA-2 coupler, if necessary.

2. Attach the BTE hearing aid to the HA-2 coupler.

3. Place the coupler/hearing-aid assembly on a foam pad outside the test box, 2 ft. (60 cm) from the transmitter during testing.

BTE aid with silhouette coil (Figure 1.1.1C)

1. Attach the ear-level adapter to the HA-2 coupler, if necessary.

2. Attach the BTE hearing aid to the HA-2 coupler.

3. Place the coupler/hearing-aid assembly on a foam pad outside the text box, 2 ft. (60 cm) from the transmitter during testing. Choose a location free of stray magnetic fields (away from video monitors and other electrical devices). It may be necessary to turn the analyzer ’s video monitor off during testing.

4. Align the silhouette coil underneath the hearing aid, simulating the way it would be worn on the ear.

Receiver

Foam Pad Foam Pad Foam Pad

to Analyzer to Analyzer to Analyzer

Receiver

Page 9

Testing FM Systems with FONIX 6500-CX Analyzers

BTE aid with neck loop (Figure 1.1.1D)

1. Within the range of the coupler microphone cable, choose a location to seat the listener that is free of stray magnetic fields (away from video monitors and other electrical devices), while also maintaining the required separation (2 ft./60 cm) from the transmitter. It may be necessary to turn the analyzer’s video monitor off during testing.

2. Place the neck loop around the listener’s neck or around the neck of a person of similar size.

3. Attach the listener ’s hearing aid to the HA-2 coupler.

4. While holding the coupler in hand, place the hearing aid at the listener ’s ear, as typically worn.

5. Take care not to move or touch the coupler microphone while testing.

Figure 1.1.1D

Neck loop

FM Receiver

to Analyzer

Page 10

Section 1: Coupler Tests of FM Systems

1.1.2 Hearing Aid Setup

1. Make sure the sound chamber is leveled.

2. Attach the hearing aid, set to user settings, to the HA-2 coupler in the usual way. Be sure the FM transmitter is off and the aid is set to receive the signal from the hearing aid microphone. See Figure 1.1.2.

3. Insert the coupler microphone into the coupler.

4. Place the assembly into the sound chamber.

5. Close and latch the sound chamber door.

Figure 1.1.2

Hearing aid setup with FM boot

1.1.3 FM System

1. Make sure the sound chamber is leveled.

2. Set the FM receiver to receive FM-only.

3. Insert the coupler microphone into the HA-2 coupler and attach the output of the FM receiver as explained in Section 1.1.1, and place at least 2 ft. (60 cm) from all transmitter parts. See Figure 1.1.3A.

4. Place the FM transmitting microphone at the test position in the chamber.

5. Close the lid and latch the chamber.

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Testing FM Systems with FONIX 6500-CX Analyzers

Figure 1.1.3A

FM setup

Isolating the environmental microphone

When the FM system is usually used in FM+ENV mode, the testing procedures call for the environmental microphone to be turned on as well at the FM microphone. In most quiet testing environments, this will call for the FM setup described above. However, if you are testing in a noisy environment, you may want to isolate the environmental microphone from the room noise.

To check if you need to provide sound isolation for the environmental microphone when testing the FM microphone in FM+ENV mode, do this procedure:

1. Set the FM microphone up for testing as described above.

2. Set the FM receiver to receive FM only.

3. Observe the RMS OUT for this FM-only signal.

4. Set the FM receiver to receive FM+ENV.

5. Observe the RMS OUT for the FM+ENV setting. If the RMS OUT is more than 3 dB higher for FM+ENV than for FM-only, then you will need to isolate the environmental microphone when testing the FM microphone in FM+ENV mode. If the RMS OUT for both signals is within 3 dB, no additional setup is necessary.

6. To isolate the environmental microphone, it is preferable to use a spare sound chamber if one is available to you. Otherwise, take a shoebox, line it with packing foam, and place the environmental microphone inside, covering it with some more foam. See Figure 1.1.3B. This should isolate the room noise from the environmental microphone.

Transmitter

Receiver

Foam Pad

6500 Main

Electronics Module

Test Chamber

2 ft.

(60 cm)

FM Mic

(or Environmental Mic)

Page 12

Section 1: Coupler Tests of FM Systems

Figure 1.1.3B

Isolating the environmental microphone

1.1.4 Environmental Microphone Setup

Environmental microphones on ear-level FM receivers

1. Make sure the sound chamber is leveled.

2. Attach the ear-level FM receiver to the HA-2 coupler and set it to receive input from the environmental microphone only.

3. Insert the coupler microphone into the HA-2 coupler.

4. Place the ear-level receiver and coupler at the test position in the sound chamber.

5. Close and latch the sound chamber lid.

6. You are now ready to test the FM system with the signal delivered to the environmental microphone.

Shoebox lined

with foam

Isolate

environmental

microphone

FM mic

Page 13

Testing FM Systems with FONIX 6500-CX Analyzers

Lapel environmental microphones on Body-worn FM Receivers

1. Make sure the sound chamber is leveled.

2. Attach the output transducer from the FM receiver to the HA-2 coupler outside the sound chamber as described in Section 1.1.1.

3. Insert the coupler microphone into the HA-2 coupler.

4. Place the lapel microphone from the FM receiver at the test position in the sound chamber. See Figure 1.1.4.

5. Close and latch the lid of the sound chamber.

6. You are now ready to test the FM system with the signal delivered to the environmental microphone.

Figure 1.1.4

Testing lapel receivers

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Section 1: Coupler Tests of FM Systems

1.2 Omni-directional: FM-only

This section contains a description of the four different coupler measurements of FM systems when the client primarily uses the system in FM-only mode. These measurements are:

• EHA65: typical electroacoustic response of the aid

• EFM80: typical electroacoustic response of the FM transmitter/receiver

• EHA90: saturation electroacoustic response of the aid

• EFM90: saturation electroacoustic response of the FM transmitter/receiver

1.2.1 Test aid alone with typical input — EHA65

1. Set up the hearing aid according to the hearing aid setup described in Section 1.1.2.2. Press [RESET] to enter Composite Weighted Gain Mode.

3. Press [WEIGHT] to enter Composite Weighted Power Mode. The display will be labeled as OUTPUT SPL.

4. Use [∨] to set RMS Source to 65 dB SPL.

5. Once the curve is stable, press [FREEZE] to pause the measurement. If the 6500-CX has the Multi-Curve Option, press [START] (not [CONTINUE]!) to save the curve into the Multi-Curve stack. For units without Multi-Curve, press [CRT] to print the measurement.

6. This will be referred to as the Electroacoustic Hearing Aid Response or EHA65. See Figure 1.2.1.

Figure 1.2.1

EHA65—hearing aid response at 65 dB SPL

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Testing FM Systems with FONIX 6500-CX Analyzers

1.2.2 Test FM microphone with typical input — EFM80

1. Set up the FM system according to the FM system setup in Section 1.1.3.

2. Use [∧] to adjust the signal level to 80 dB SPL.

3. This curve will be referred to as the Electroacoustic FM Response or EFM80. (Since the current running curve is always stored as CRV 1 in the Multi-Curve buffer, there is no need to press [FREEZE] and [START] to save the curve as you did in Section

1.2.1.)

4. To view the EFM80 and EHA65 on the same screen requires the Multi-Curve Option: a. Press [MULTI]. b. Highlight MULTIPLE CURVES. c. Press [START]. d. If necessary, use [<, >] to display CRV 1 in the first slot. This curve is EFM80. e. Use [∨] to select the second slot. f. If necessary, use [<, >] to display CRV 2 in the second slot. This curve is EHA65.

See Figure 1.2.2.

If you don’t have the Multi-Curve Option, press [CRT] to print out EFM80 and compare it to EHA65.

Figure 1.2.2

Comparison of EHA65 (CRV2), the hearing aid response at 65 dB

SPL and EFM80 (CRV1), the FM response at 80 dB SPL

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Section 1: Coupler Tests of FM Systems

5. If you have a client with a mild to moderate hearing loss (less than 80 dB HL), the output of the two curves should be within 5 dB of each other. If you have a client with a severe to profound loss (greater than 80 dB HL), the output of EFM80 should be 7-10 dB higher than the output of EHA65.

If you have to adjust the system to obtain a better result, first adjust the FM receiver volume control if possible. When using FM systems coupled to personal hearing aids adjust the settings on the hearing aid as a final step if necessary. If this must be done, the teacher, parents, and therapists must be made aware that when the FM system is used, the settings on the hearing aid must be changed for optimum performances.

1.2.3 Test aid alone with high-level input — EHA90

1. Turn off the FM signal, and set up the hearing aid for testing as described in the hearing aid setup in Section 1.1.2.

2. Press [SINE/COMPOSITE] button to enter Pure Tone Mode. The analyzer will automatically set itself to a signal level of 90 dB SPL.

3. Press [START] to begin the pure-tone sweep. The response will be stored in the Multi-Curve stack when the measurement is complete. For instruments without the Multi-Curve option, press [CRT] to print a hardcopy.

Figure 1.2.3

EHA90—hearing aid response at 90 dB SPL

4. This response will be referred to as the Electroacoustic Hearing Aid Saturation Response or EHA90. See Figure 1.2.3.

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Testing FM Systems with FONIX 6500-CX Analyzers

1.2.4 Test FM system with high-level input — EFM90

1. Set up the FM system for testing according to the FM setup in Section 1.1.3. The FM receiver should be set to receive FM-only signals.

2. Press [START] to begin the pure-tone sweep. The response will be stored in the Multi-Curve stack when the measurement is complete. For instruments without the Multi-Curve option, press [CRT] to print a hardcopy.

3. This response will be referred to as the Electroacoustic FM Saturation Response or EFM90.

Figure 1.2.4

Comparison of EHA90 (CRV2), the hearing aid response at 90 dB

SPL with EFM90 (CRV1), the FM response at 90 dB

4. To view both curves on the same screen requires the Multi-Curve Option: a. Press [MULTI]. b. Highlight MULTIPLE CURVES. c. Press [START]. d. If necessary, use [<, >] to display CRV 1 in the first slot. This curve is EFM90. e. Use [∨] to select the second slot. f. If necessary, use [<, >] to display CRV 2 in the second slot. This curve is EHA90.

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Section 1: Coupler Tests of FM Systems

g. You may want to press [∨] and [FREEZE] to turn off the display of CRV 3, since

it is not relevant to this comparison. Similarly, press [∨] and [FREEZE] again to turn off the display of CRV 4.

If you don’t have the Multi-Curve Option, press [CRT] to print out EFE90 and compare it to EHA90.

5. If EFM90 is greater than 5 dB above or 10 dB below EHA90, adjust the maximum output control if possible on the FM receiver or on the hearing aid if necessary. If the hearing aid is adjusted, the teacher, parents, and therapists must be made aware that when the FM system is used, the settings on the hearing aid must be changed for optimum performances. For mild to moderate losses it may be acceptable if the EFM90 is 5-10 dB below EHA90. See Figure 1.2.4.

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Testing FM Systems with FONIX 6500-CX Analyzers

1.3 Omni-directional: FM+ENV

This section contains a description of the different coupler measurements of omni-directional FM systems when the client primarily uses the system with the environmental microphone added to the FM signal (FM+ENV mode). These measurements are:

• Response of aid with 65 dB SPL signal at 1 kHz

• Response of FM transmitter/receiver with 65 dB SPL signal at 1 kHz

• Verify increase of FM transmitter/receiver when signal level is increased to 80 dB SPL.

• EHA65: typical electroacoustic response of the aid

• EFE80: typical electroacoustic response of the FM transmitter/receiver

• EEF65: typical electroacoustic response of environmental microphone

• EHA90: saturation electroacoustic response of the aid

• EFE90: saturation electroacoustic response of the FM transmitter/receiver

• EEF90: saturation electroacoustic response of environmental microphone

1.3.1 Single frequency output of omni-directional hearing aid in the sound chamber

1. Set up the hearing aid for testing as described in the hearing aid setup in Section

1.1.2. The FM transmitter should be off, and the hearing aid set to receive input from the hearing aid microphone.

2. Press [RESET].

3. Press [SINE/COMPOSITE] to put the analyzer in PURE TONE MODE.

4. If necessary, use [<, >] to adjust the frequency of the single tone signal to 1000 Hz.

Figure 1.3.1

Hearing aid output at 65 dB SPL at 1000 Hz

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Section 1: Coupler Tests of FM Systems

5. Use [∨] to adjust the level of the signal to 65 dB SPL.

6. Make a note of the AID OUT on the screen. This is the HEARING AID OUTPUT. See Figure 1.3.1.

1.3.2 Single frequency output of omni-directional FM mic at 65 dB SPL

1. Set up the FM microphone for testing as described in the FM setup in Section 1.1.3. The FM receiver should be set to receive FM+ENV.

2. If you followed the steps of Section 1.3.1, the analyzer should be in PURE TONE MODE with a 65 dB SPL signal at 1000 Hz.

3. Look at the AID OUT on the screen. This is the FM OUTPUT.

4. Adjust the FM receiver volume so that the FM OUTPUT is matched to the HEARING AID OUTPUT found in Section 1.3.1. This matches the gain of the FM system and the hearing aid.

1.3.3 Verify increase in signal level

1. Leave the FM system and analyzer set up as described in Section 1.3.2 with the aid or FM receiver attached to the 2-cc coupler and set to receive FM+ENV.

2. Press [∧] repeatedly to increase the signal level to 80 dB SPL.

3. Look at the AID OUT on the screen. This is the new FM OUTPUT.

4. Compare the HEARING AID OUTPUT found in Section 1.3.1 to this new FM OUTPUT, and adjust the FM receiver volume control according to the following:

If the increase is:

• 10 dB, no further adjustments are necessary.

• 15 dB, reduce the FM receiver volume control so that the FM OUTPUT falls by 5 dB.

• 5 dB, increase the FM receiver volume control so that the FM OUTPUT increases

by 7 or 8 dB.

• 0 dB, the FM transmitter must have a very low compression threshold, so

increase the FM receiver volume control so that the FM OUTPUT increases by 5 dB.

1.3.4 Test aid alone with typical input — EHA65

1. Set up the hearing aid for testing as described in Section 1.1.2. The FM transmitter should be off, and the hearing aid set to receive input from the hearing aid microphone.

2. Press [RESET] to enter Composite Weighted Gain Mode.

3. Press [WEIGHT] to enter Composite Weighted Power Mode.

4. Use [∨] to set RMS Source to 65 dB SPL.

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Testing FM Systems with FONIX 6500-CX Analyzers

Figure 1.3.4

EHA65—hearing aid response at 65 dB SPL

6. This will be referred to as the Electroacoustic Hearing Aid Response or EHA65. See Figure 1.3.4.

1.3.5 Test FM+ENV microphones with typical input to FM microphone — EFE80

1. Set up the FM system according to Section 1.1.3. The FM receiver should be set to receive FM+ENV.

2. Use [∧] to adjust the signal level to 80 dB SPL.

3. This curve will be referred to as the Electroacoustic FM Response or EFE80.

4. To view the EFE80 and EHA65 on the same screen requires the Multi-Curve Option: a. Press [MULTI]. b. Highlight MULTIPLE CURVES. c. Press [START]. d. If necessary, use [<, >] to display CRV 1 in the first slot. This curve is EFE80 or

the Electroacoustic FM and Environmental Response with 80 dB input to the FM microphone.

e. Use [∨] to select the second slot.

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Section 1: Coupler Tests of FM Systems

f. If necessary, use [<, >] to display CRV 2 in the second slot. This curve is EHA65. If you don’t have the Multi-Curve Option, press [CRT] to print out EFE80 and com-

pare it to EHA65.

Figure 1.3.5

Comparison of EHA65 (CRV2), the hearing aid response at 65 dB

SPL and EFM80 (CRV1), the FM response at 80 dB SPL

5. Compare EHA65 (CRV 2) to EFE80 (CRV 1) to confirm that the desired FM advantage is maintained over the 500 to 2000 Hz range. In general, that advantage should be 7-10 dB. See Figure 1.3.5.

6. For units with Multi-Curve, you will want to save EFE80 for a comparison in the next section. To do this:

a. Press [CONTINUE] twice to exit from Multi-Curve. b. Press [FREEZE] to save the current EFE80 measurement. c. Press [START] to save the curve to the Multi-Curve stack. EFE80 has just become

CRV 2 and EHA65 has just become CRV 3. You will use them in the next section.

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Testing FM Systems with FONIX 6500-CX Analyzers

1.3.6 Test environmental microphone response with typical input—EEF65

1. Set up the environmental microphone for testing as described in Section 1.1.4. Set the FM receiver to receive FM+ENV signals.

2. Use [∨] to set the source level to 65 dB SPL and wait for the response to stabilize.

3. This measurement will be referred to as EEF65, or the Electroacoustic FM and Environmental Response with 65 dB SPL input to the environmental microphone.

4. Compare EEF65 to EHA65 (from Section 1.3.4) and EFE80 (from Section 1.3.5). If you have Multi-Curve, do the following:

a. Press [MULTI]. b. Highlight MULTIPLE CURVES. c. Press [START]. d. CRV 1 will be selected for the first Multi-Curve slot. This is the EEF65 response.

CRV 2 should be selected for the second Multi-Curve slot. This is the EFE80 response. Use [∨] to select the third Multi-Curve slot.

e. Use [<, >] to select CRV 3 for the third Multi-Curve slot. This is the EHA65

response.

f. Compare EEF65 (CRV 1), EFE80 (CRV 2), and EHA65 (CRV 3). For a successful

fit, the EHA65 and EEF65 should be similar, and the EFE80 should be 7-10 dB higher. See Figure 1.3.6.

Figure 1.3.6

Comparison of EHA65 (CRV1), EFM80 (CRV2), and EEF65, the

environmental microphone response at 65 dB SPL

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Section 1: Coupler Tests of FM Systems

1.3.7 Test aid alone with high-level input — EHA90

1. Turn off the FM signal, and set up the hearing aid for testing as described in Section

1.1.2.

2. Press [SINE/COMPOSITE] button to enter Pure Tone Mode. The analyzer will automatically set itself to a signal level of 90 dB SPL.

4. This response will be referred to as the Electroacoustic Hearing Aid Saturation Response or EHA90. See Figure 1.3.7.

Figure 1.3.7

EHA90—the hearing aid response at 90 dB SPL

1.3.8 Test with FM system using a high-level input — EFE90

1. Set up the FM system for testing according to Section 1.1.3. The FM receiver should be set to receive FM+ENV.

3. This response will be referred to as EFE90 or the Electroacoustic FM and Environmental Response with 90 dB SPL input to the FM microphone.

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Testing FM Systems with FONIX 6500-CX Analyzers

Figure 1.3.8

Comparison of EHA90, the hearing aid response at 90 dB SPL, and

EFM 90, the FM response at 90 dB SPL

4. To view both curves on the same screen requires the Multi-Curve Option: a. Press [MULTI]. b. Highlight MULTIPLE CURVES. c. Press [START]. d. If necessary, use [<, >] to display CRV 1 in the first slot. This curve is EFE90. e. Use [∨] to select the second slot. f. If necessary, use[<, >] to display CRV 2 in the second slot. This curve is EHA90. g. You may want to press [∨] and [FREEZE] to turn off the display of CRV 3, since

it is not relevant to this comparison. Similarly, press [∨] and [FREEZE] again to turn off the display of CRV 4.

If you don’t have the Multi-Curve Option, press [CRT] to print out EFE90 and compare it to EHA90.

5. If EFE90 is greater than 5 dB above EHA90, adjust the FM system to obtain a better match. As a last resort, adjust the settings on the hearing aid. If this must be done, the teacher, parents, and therapists must be made aware that when the FM system is used, the settings on the hearing aid must be changed for optimum performances. See Figure 1.3.8.

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Section 1: Coupler Tests of FM Systems

1.3.9 Test environmental mic response with high-level input — EEF90

1. Set up the environmental microphone for testing as described in Section 1.1.4. Set the FM receiver to FM+ENV.

2. Press [START/STOP] to run a pure-tone measurement at 90 dB SPL.

3. This measurement will be referred to as EEF90 or the Electroacoustic FM and Environmental Response with 90 dB SPL input to the environmental microphone.

4. To view both curves on the same screen requires the Multi-Curve Option: a. Press [MULTI]. b. Highlight MULTIPLE CURVES. c. Press [START]. d. EEF90 (CRV 1) should be displayed in the first slot, and EFE90 (CRV 2) should

be displayed in the second slot.

e. Press [∨] to select the third slot. f. If necessary, press [<, >] to select CRV 3 for the third slot. This is the EHA90

measurement.

5. Compare EEF90 (CRV 1) to EFE90 (CRV 2) and EHA90 (CRV 3). All three curves should match. See Figure 1.3.9.

Figure 1.3.9

Comparison of EHA90, EFM90, and EFF90, the environmental

microphone response at 90 dB SPL

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Testing FM Systems with FONIX 6500-CX Analyzers

Testing FM Systems with FONIX FP40 Analyzers

1.4 Coupler Setup in the Sound Field

When testing a FM system with a large or directional microphone, the measurements are performed in the sound field. Therefore, the corresponding hearing aid tests will also have to be performed in the sound field. This requires a little creativity; you may have to adjust the following recommended procedure to fit the particular equipment that you are testing.

1.4.1 Hearing Aid Setup

1. Enter the Real Ear Mode by pressing [START/STOP] on the remote module. All further key presses described in this section will be performed on the remote module.

2. Affix the reference microphone with Fun-Tak to the platform at the top of the floor stand, 6 inches (15 cm) in front of the sound field speaker, with the microphone pointing toward the speaker. See Figure 1.4.1A. (If you don’t have a floor stand, the back of a chair can suffice. But be sure the chair is facing to the side of the setup to avoid reflections from the back of the chair.)

Figure 1.4.1A

Sound field leveling setup

3. Stand clear of the test area, holding the remote module.

4. Press [LEVEL] on the remote module.

5. Remove the reference microphone and the platform from the floor stand, leaving the floor stand in its position in front of the sound field speaker.

6. Attach the hearing aid to the HA-2 coupler.

6 inches

Reference mic

Probe mic (not used)

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Section 1: Coupler Tests of FM Systems

7. Thread a probe tube through the black probe tube adapter with the tube first entering the ridged end of the adapter. The tube should extend 1-2 mm past the other end of the adapter. Use Fun-Tak to secure the probe tube to the adapter. See Figure

1.4.1B.

Figure 1.4.1B

Thread probe tube through probe mic adapter

8. Insert the adapter into the HA-2 coupler, and attach the probe tube to the probe microphone. See Figure 1.4.1C.

Figure 1.4.1C

Attach coupler to probe mic

Probe mic

Probe mic adapter

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Testing FM Systems with FONIX 6500-CX Analyzers

9. Securely attach the assembly to the floor stand using Fun-Tak. The body of the hearing aid should be vertical with the hearing aid microphone pointed towards the sound field speaker. See Figure 1.4.1D.

Figure 1.4.1.D

Setup for testing a hearing aid in the sound field using a coupler

10. You are now ready to test the hearing aid.

1.4.2 FM System Setup

Since the tests of the FM transmitter/receiver in this chapter always follow the tests of the hearing aid, it is assumed in this setup that you have already entered Real Ear Mode and leveled the sound field speaker. If you are testing out of order, follow the instructions found in Section 1.4.1, Steps 1-4, to level the sound field before testing.

1. Place the FM transmitting microphone on the floor stand six inches (15 cm) from the sound field speaker. Keep all sound-entry ports clear of the platform. Place the transmitter and its cord behind the transmitting microphone.

2. Thread a probe tube through the black probe tube adapter with the tube first entering the ridged end of the adapter. The tube should extend 1-2 mm past the other end of the adapter. Use Fun-Tak to secure the probe tube to the adapter. See Figure

1.4.1B.

3. Insert the adapter into the HA-2 coupler, and attach the probe tube to the probe microphone. See Figure 1.4.1C.

4. Attach the FM receiver to the HA-2 coupler as described in Section 1.1.1.

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Section 1: Coupler Tests of FM Systems

5. Place the assembly 2 ft (60 cm) from the transmitting microphone, out of the sound field of the speaker. See Figure 1.4.2.

6. Stand clear of the test area, holding the remote module. You are now ready to test the FM transmitter/receiver.

Figure 1.4.2

FM setup system

Isolating the environmental microphone

The testing procedures in this section call for the environmental microphone to be turned on as well at the FM microphone. In most quiet testing environments, this will call for the FM setup described in Section 1.4.1. However, if you are testing in a noisy environment, you may want to isolate the environmental microphone from the room noise.

To check if you need to provide sound isolation for the environmental microphone when testing the FM microphone in FM+ENV mode, do this procedure:

1. Set the FM microphone up for testing as described in Section 1.1.3.

2. Set the FM receiver to receive FM only.

3. Press [START/STOP] on the remote module to start a composite measurement. When the measurement stabilizes, press [START/STOP] again.

4. Observe the RMS OUT for this FM-only signal.

5. Set the FM receiver to receive FM+ENV.

6. Repeat Step 3.

Reference mic

FM mic

(not used)

Probe mic

FM receiver

FM transmitter

attached

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Testing FM Systems with FONIX 6500-CX Analyzers

7. Observe the RMS OUT for the FM+ENV setting. If the RMS OUT is more than 3 dB higher for FM+ENV than for FM-only, then you will need to isolate the environmental microphone when testing the FM microphone in FM+ENV mode. If the RMS OUT for both signals is within 3 dB, no additional setup is necessary.

8. To isolate the environmental microphone, it is preferable to use a spare sound chamber if one is available to you. Otherwise, take a shoebox, line it with packing foam, and place the environmental microphone inside, covering it with some more foam. See Figure 1.1.3B. This should isolate the room noise from the environmental microphone.

1.4.3 Environmental microphones on body-worn receivers

1. Enter Real Ear Mode by pressing [START/STOP] on the remote module or [PROBE] on the 6500-CX main module.

2. Affix the FM receiver to the platform stand in the manner shown in Figure 1.4.3A.

Figure 1.4.3A

Attaching reference microphone

3. Using Fun-Tak, affix the reference microphone to the receiving unit so the entrance to the reference microphone is very close to that of the environmental microphone.

4. Place the FM receiver six inches (15 cm) from, and facing, the loudspeaker (Refer to Figure 1.4.3B) and set it to receive input from the environmental microphone only.

5. Choose a place to stand during testing, preferably away from the loudspeaker and microphone, holding the remote module. Stand precisely in this place during both leveling and testing.

6. Press [LEVEL] on the remote module. This levels the test signal at the place where the FM receiver microphone will be during testing.

7. Leave the reference microphone in place during testing.

Reference Microphone

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Section 1: Coupler Tests of FM Systems

8. Thread the probe tube through the probe tube adapter so that it extends 3 mm past the end. Use Fun-Tak to hold the probe tube in place. See Figure 1.4.1B.

9. Insert the adapter and probe tube (attached to the probe microphone) into the HA-2 coupler, and attach to the button earphone, direct audio input hearing aid, or aid coupled with neck loop or silhouette, as explained in Section 1.1.

10. You are now ready to test the FM system with the signal delivered to the environmental microphone.

Figure 1.4.3B

Leveling the sound field

Figure 1.4.3C

Testing with body-worn receiver

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Testing FM Systems with FONIX 6500-CX Analyzers

1.5 Directional: Testing FM-only

This section contains a description of the four different coupler measurements of FM systems when the client primarily uses the system in FM-only mode. These measurements are:

• EHA65: typical electroacoustic response of the aid

• EFM80: typical electroacoustic response of the FM transmitter/receiver

• EHA90: saturation electroacoustic response of the aid

• EFM90: saturation electroacoustic response of the FM transmitter/receiver

1.5.1 Test aid alone with typical input — EHA65

1. Follow the hearing aid setup instructions found in Section 1.4.1 to set up the hearing aid for testing the sound field, enter Real Ear Mode, and level the sound field speaker. The FM transmitter should not be on and the aid should be set to receive the hearing aid microphone.

2. Press [MENU] on the remote module.

3. Press [∨] to highlight CREATE TARGET.

4. Press [<, >] to select SPL TARGET.

5. Press [START/STOP] twice. This will open the SPL Test Screen.

Figure 1.5.1

EHA65—the hearing aid response at 65 dB SPL

6. Look in the bottom left corner of your screen. If it says AUTO, press [UNAIDED] on the remote module. This will put you in MANUAL Mode.

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Section 1: Coupler Tests of FM Systems

7. Press [MENU] to enter the SPL Menu.

8. Select COMP for AIDED CURVE 1 and AIDED CURVE 2.

9. Press [MENU] to return to the SPL Test Screen.

10. If necessary, select CRV 1 with [∧].

11. Use [<, >] to select a source level of 65 dB SPL.

12. Press [START/STOP] to begin the measurement.

13. Press [START/STOP] once the measurement has stabilized. This curve is the Electroacoustic Hearing Aid Response or EHA65. See Figure 1.5.1.

1.5.2 Test FM microphone with typical input — EFM80

1. Set up the FM system for testing according to FM setup described in Section 1.4.2.

2. Use [∨] to select CRV 2.

3 Use [<, >] to set the RMS source to 80 dB SPL.

4. Press [START/STOP] to start the measurement.

5. Once the measurement stabilizes, press [START/STOP] again to stop the measurement.

Figure 1.5.2

Comparison of EHA65 (CRV1), the hearing aid response at 65 dB

SPL and EFM80 (CRV2), the FM response at 80 dB SPL

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Testing FM Systems with FONIX 6500-CX Analyzers

6. CRV 2 is now the Electroacoustic FM Response or EFM80.

7. If you have a client with a mild to moderate hearing loss (less than 80 dB HL), the output of the two curves should be within 5 dB of each other. If you have a client with a severe to profound loss (greater than 80 dB HL), the output of EFM80 should be 7-10 dB higher than the output of EHA65.

1.5.3 Test aid alone with high-level input — EHA90

1. Set up the hearing aid for testing in the sound field by following the directions found in the hearing aid setup in Section 1.4.1. If you’ve already leveled the sound field speaker, you can skip to step 6 in that section.

2. Press [MENU] to enter the SPL Menu.

3. Select PURE TONE for AIDED CURVE 1 and AIDED CURVE 2.

4. Press [MENU] to return to the SPL Test Screen.

5. Press [∧] to select CRV 1.

Figure 1.5.3

EHA90—the hearing aid response at 90 dB SPL

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Section 1: Coupler Tests of FM Systems

6. Use [>] to select a source level of 90 dB SPL.

7. Press [START/STOP] to begin the sweep.

8. This response will be referred to as the Electroacoustic Hearing Aid Saturation Response or EHA90. See Figure 1.5.3.

1.5.4 Test FM system with high-level input — EFM90

1. Set up the FM system for testing according to the FM setup described in Section

1.4.2.

2. Use [∨] to select CRV 2.

3. Use [>] to select a source level of 90 dB SPL.

4. Press [START/STOP] to make the measurement.

5. CRV 2 is now the Electroacoustic FM Saturation Response or EFM90.

6. Compare EHA90 (CRV 1) to EFM90 (CRV 2). If EFM90 is greater than 5 dB above or 10 dB below EHA90, adjust the maximum output control if possible on the FM receiver or on the hearing aid if necessary. If the hearing aid is adjusted, the teacher, parents, and therapists must be made aware that when the FM system is used, the settings on the hearing aid must be changed for optimum performances. For mild to moderate losses it may be acceptable if the EFM90 is 5-10 dB below EHA90. See Figure 1.5.4.

Figure 1.5.4

Comparison of EHA90 (CRV1), the hearing aid response at 90 dB

SPL with EFM90 (CRV2), the FM response at 90 dB SPL

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Testing FM Systems with FONIX 6500-CX Analyzers

1.6 Directional: Testing FM+ENV

This section contains a description of the different coupler measurements of FM systems when the client primarily uses the system with the environmental microphone added to the FM signal (FM+ENV mode). These measurements are:

• Response of aid with 65 dB SPL signal at 1 kHz

• Response of FM transmitter/receiver with 65 dB SPL signal at 1 kHz

• Verify increase of FM transmitter/receiver when signal level is increased to 80 dB SPL.

• EHA65: typical electroacoustic response of the aid

• EFE80: typical electroacoustic response of the FM transmitter/receiver

• EEF65: typical electroacoustic response of environmental microphone

• EHA90: saturation electroacoustic response of the aid

• EFE90: saturation electroacoustic response of the FM transmitter/receiver

• EEF90: saturation electroacoustic response of environmental microphone

1.6.1 Single frequency output of hearing aid

1. Set up the aid for testing according to the hearing aid setup described in Section

1.4.1. The FM transmitter should be off and the hearing aid set to receive input from the hearing aid microphone. Make sure you level the sound field speaker.

2. Press [MENU].

3. Use [∨] to highlight MODE.

4. Use [<, >] to select PURE TONE.

5. Press [MENU] to exit from the Quik-Probe II Menu.

Figure 1.6.1

Hearing aid output at 65 dB SPL at 1000 Hz

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Section 1: Coupler Tests of FM Systems

6. Press [START/STOP] to begin a single frequency signal.

7. If necessary, use [<, >] to adjust the frequency to 1000 Hz.

8. Use [∨, ∧] to adjust the signal level to 65 dB SPL.

9. Note the MIC OUT on the screen. This is the HEARING AID OUTPUT. See Figure

1.6.1.

10. Press [START/STOP] to turn off the signal.

1.6.2 Single frequency output of FM mic at 65 dB SPL

1. Set up the FM system for testing according to Section 1.4.2. The FM receiver should be set to receive FM+ENV.

2. If you followed the procedure described in Section 1.6.1, you should be in Real Ear Mode, with the analyzer ready to deliver a pure-tone signal of 1000 Hz at 65 dB SPL.

3. Press [START/STOP] to start the measurement.

4. Note the AID OUT on the screen. This is the FM OUTPUT.

5. Adjust the FM receiver volume so that the FM OUTPUT is matched to the HEARING AID OUTPUT found in Section 1.6.1. This matches the gain of the FM system and the hearing aid.

6. Press [START/STOP] to turn off the signal.

1.6.3 Verify increase in signal level

1. Leave the FM system and the analyzer set up as described in Section 1.6.2.

2. Press [START/STOP] to start the single frequency measurement.

3. Press [∧] repeatedly to increase the signal level to 80 dB SPL.

4. Note the AID OUT on the screen. This is the FM OUTPUT.

5. Compare the HEARING AID OUTPUT found in Section 1.6.1 to this new FM OUTPUT, and adjust the FM receiver volume control according to the following:

If the increase is:

• 10 dB, no further adjustments are necessary.

• 15 dB, reduce the FM receiver volume control so that the FM OUTPUT falls by 5

dB.

• 5 dB, increase the FM receiver volume control so that the FM OUTPUT increases

by 7 or 8 dB.

• 0 dB, the FM transmitter must have a very low compression threshold, so

increase the FM receiver volume control so that the FM OUTPUT increases by 5 dB.

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Testing FM Systems with FONIX 6500-CX Analyzers

1.6.4 Test aid with typical input — EHA65

2. Press [MENU] on the remote module.

3. Press [∨] to highlight CREATE TARGET.

4. Press [<, >] to select SPL TARGET.

5. Press [START/STOP] twice. This will open the SPL Test Screen.

6. Look in the bottom left corner of your screen. If it says AUTO, press [UNAIDED] on the remote module. This will put you in MANUAL Mode.

7. Press [MENU] to enter the SPL Menu.

8. Select COMP for AIDED CURVE 1, AIDED CURVE 2, and AIDED CURVE 3.

9. Press [MENU] to return to the SPL Test Screen.

10. If necessary, select CRV 1 with [∧].

11. Use [<, >] to select a source level of 65 dB SPL.

Figure 1.6.4

Hearing aid response at 65 dB SPL

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Section 1: Coupler Tests of FM Systems

12. Press [START/STOP] to begin the measurement.

13. Press [START/STOP] once the measurement has stabilized. This curve is the Electroacoustic Hearing Aid Response or EHA65. See Figure 1.6.4.

1.6.5 Test FM+ENV microphones with typical input to FM microphone — EFE80

1. Set up the FM system for testing according to the FM setup described in Section

1.4.2. The FM receiver should be set to receive FM+ENV. If you’ve already leveled the sound field speaker, you can skip to step 5 in that section.

2. Use [∨] to select CRV 2.

3 Use [<, >] to set the RMS source to 80 dB SPL.

4. Press [START/STOP] to start the measurement.

5. Once the measurement stabilizes, press [START/STOP] again to stop the measurement.

6. CRV 2 is now the EFE80 or the Electroacoustic FM and Environmental Response with 80 dB input to the FM microphone.

7. Compare EHA65 (CRV 2) to EFE80 (CRV 1) to confirm that the desired FM advantage is maintained over the 500 to 2000 Hz range. In general, that advantage should be 7-10 dB. See Figure 1.6.5.

Figure 1.6.5

Comparison of EHA65 (CRV1), the hering aid response at 65 dB SPL

with EFM80 (CRV2), the FM response at 80 dB SPL

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Testing FM Systems with FONIX 6500-CX Analyzers

1.6.6 Test environmental mic response with typical input — EEF65

1. Set up the environmental microphone for testing as described in Section 1.4.3. Set the FM receiver to receive FM+ENV signals. If the sound field speaker is leveled, you don’t have to re-level it.

2. Press [∨] to select CRV 3.

3. Press [<, >] to set the source level to 65 dB SPL.

4. Press [START/STOP] to start the measurement.

5. When the measurement has stabilized, press [START/STOP] again to stop the measurement. This measurement will be referred to as EEF65.

6. Compare all three curves. CRV 1 should be EHA65, CRV 2 should be EFE80, and CRV 3 should be EEF65. For a successful fit, EHA65 and EEF65 should be similar, and EFE80 should be 7-10 dB higher. See Figure 1.6.6.

Figure 1.6.6

Comparison of EHA65 (CRV1), EFM 80 (CRV2), and EEF65 (CRV),

the environmental microphone response at 65 dB SPL

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Section 1: Coupler Tests of FM Systems

1.6.7 Test aid with high-level input — EHA90

2. Press [MENU] to enter the SPL Menu.

3. Select PURE TONE for AIDED CURVE 1, AIDED CURVE 2, and AIDED CURVE 3.

4. Press [MENU] to return to the SPL Test Screen.

5. Press [∧] to select CRV 1.

6. Use [>] to select a source level of 90 dB SPL.

7. Press [START/STOP] to begin the sweep.

8. This response will be referred to as the Electroacoustic Hearing Aid Saturation Response or EHA90. See Figure 1.6.7.

Figure 1.6.7

EHA90—the hearing aid response at 90 dB SPL

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Testing FM Systems with FONIX 6500-CX Analyzers

1.6.8 Test with FM system using a high-level input — EFE90

1. Set up the FM system for testing according to the FM setup described in Section

1.4.2. The FM receiver should be set to receive FM+ENV. If you’ve already leveled the sound field speaker, you can skip to step 5 in that section.

2. Use [∨] to select CRV 2.

3. Use [>] to select a source level of 90 dB SPL.

4. Press [START/STOP] to make the measurement.

5. CRV 2 is now the Electroacoustic FM Saturation Response or EFE90.

6. Compare EHA90 (CRV 1) to EFE90 (CRV 2). See Figure 1.6.8. If EFE90 is greater than 5 dB above EHA90, adjust the FM system to obtain a better match. As a last resort, adjust the settings on the hearing aid. If this must be done, the teacher, parents, and therapists must be made aware that when the FM system is used, the settings on the hearing aid must be changed for optimum performances.

Figure 1.6.8

Comparison of EHA90 (CRV1), the hearing aid response at 90 dB

SPL with EFM90 (CRV2), the FM response at 90 dB SPL

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Section 1: Coupler Tests of FM Systems

1.6.9 Test environmental mic response with high-level input — EEF90

1. Set up the environmental microphone for testing as described in Section 1.4.3. Set the FM receiver to FM+ENV. If the sound field speaker is already leveled, you don’t have to re-level it.

2. Press [∨] to select CRV 3.

3. Press [START/STOP] to take the measurement.

4. This measurement will be referred to as EEF90 or the Electroacoustic FM and Environmental Response with 90 dB SPL input to the environmental microphone.

5. Compare EEF90 (CRV 3) to EFE90 (CRV 2) and EHA90 (CRV 1). All three curves should match. See Figure 1.6.9.

Figure 1.6.9

Comparison of EHA90, EFM90, and EEF90, the environmental

microphone’s response at 90 dB SPL

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Testing FM Systems with FONIX 6500-CX Analyzers

2: Real-Ear Evaluation with FM systems

Real-ear measurements are essential for understanding the aid’s response inside the client’s ear.

• If the FM receiver is primarily set to receive FM-only signals, follow the procedures

described in Section 2.2, Testing FM-only.

• If the FM receiver is primarily set to receive FM with environmental signals (FM+ENV), follow the procedures described in Section 2.3, Testing FM+ENV.

Both of these procedures will work with directional microphones.

2.1 Setup

This section describes the real-ear setup for testing the hearing aid, FM system, and environmental microphone in a sound field using a probe microphone.

2.1.1 Hearing Aids

1. Place the sound field speaker 12-15 inches from the client, pointing towards his head at a 45º angle.

2. Place the wedge style earhook on the client’s ear.

Figure 2.1.1

Hearing aid setup

12"

Speaker

(45 degrees)

Reference Mic

Probe Mic

12"

Reference Mic

Probe Mic

Top View

Front View

Speaker

(45 degrees)

Page 46

Section 2: RealEar evaluation with FM system

3. Put the reference microphone on the wedge above the client’s ear so that it points towards the sound field speaker. See Figure 2.1.1.

4. Press [LEVEL] on the remote module. This will level the sound field speaker.

5. Mark the probe tube to ensure the desired insertion depth, and place it into the client’s ear.

6. Carefully insert the earmold attached to the hearing aid.

7. You are now ready to test the hearing aid.

2.1.2 FM System

When testing the transmitting and receiving part of the FM system in the real-ear, the FM transmitting microphone is placed in the sound field. The probe microphone and the ear piece of the FM receiver are inserted into the client’s ear, but the client remains outside of the sound field. Since FM measurements follow hearing aid measurements in all of the described sets of tests, it is assumed that the analyzer is already in Real Ear Mode.

1. Place the reference microphone on a platform at the top of a floor stand, 6 inches (15 cm) in front of and facing the loudspeaker, as in Figure 2.1.2A.

2. Choose a place to stand during testing, preferably away from the loudspeaker and microphone. Hold the remote module, so you can operate the test. Stand precisely in this place during both leveling and testing.

3. Press [LEVEL] on the remote module. This levels the sound field.

4. Remove the reference microphone and replace it with the FM transmitting microphone.

5 Mark a probe tube attached to the probe microphone to ensure the desired insertion

depth, and place the probe tube and the ear piece of the receiving unit in the client’s ear. The insertion depth of the probe tube should be the same as used to test the client’s hearing aid The client should be at least 2 ft (60 cm) from the loudspeaker to avoid being in the sound field. See Figure 2.1.2B.

6. You are now ready to test the FM transmitter/receiver.

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Testing FM Systems with FONIX 6500-CX Analyzers

Figure 2.1.2A

Leveling setup

Figure 2.1.2B

FM setup

2.1.3 Setup for Testing Environmental Microphones

If the client uses an environmental microphone with his FM system, it is important to test it to make sure that its response matches that of the client’s hearing aid. This section describes several different methods for setting up an environmental microphone for testing.

6 inches

FM transmitter

Probe mic and

FM receiver

Patient out of

sound field

6 inches

Reference mic

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Section 2: RealEar evaluation with FM system

Environmental microphones on body-worn receivers

1. Arrange the reference microphone and FM receiver environmental microphone as described in Section 1.4.3. The FM receiver will be six inches from and facing the loudspeaker.

2. Choose a place to stand during testing, preferably away from the loudspeaker and microphone. Hold the remote module so that you can operate the test. Stand precisely in this place during both leveling and testing.

3. Press [LEVEL]. This levels the sound field speaker.

4. Remove the reference microphone from the sound field. It will not be used for testing so you can lay it to one side.

5. Mark the probe tube to ensure the desired insertion depth, and place it and the ear piece of the receiving unit in the client’s ear. The insertion depth of the probe tube should be the same as used to test the client’s hearing aid The client should be at least 2 ft (60 cm) from the loudspeaker to avoid being in the sound field. 6. You are now ready to test the environmental microphone on a body-worn receiver.

Environmental microphone on a hearing aid

When the environmental microphone is on the hearing aid itself or at the ear level, use the real-ear setup described in Section 2.1.1.

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Testing FM Systems with FONIX 6500-CX Analyzers

2.2 Testing FM-Only

This section contains a description of the four different real-ear measurements of FM systems when the client primarily uses the system in FM-only mode. These measurements are:

• RHA65: real-ear typical response of the aid

• RFM80: real-ear typical response of the FM transmitter/receiver

• RHA90: real-ear saturation response of the aid

• RFM90: real-ear saturation response of the FM transmitter/receiver

2.2.1 Test aid with typical input — RHA65

1. Press [START/STOP] on the remote module or [PROBE] on the main module to enter Real-ear Mode.

2. Follow the instructions in Section 2.1.1 to level the sound field speaker and ready the client for a real-ear measurement.

3. Press [MENU].

Figure 2.2.1

RHA65—hearing aid response at 65 dB SPL

4. Highlight [CREATE TARGET] using [∨, ∧].

5. Select [SPL TARGET] using [<, >].

6. Press [START/STOP] twice. This will open the SPL Test Screen.

7. Make sure that the bottom left corner of your screen says MANUAL. If it says AUTO, press [UNAIDED] to change it to MANUAL.

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Section 2: RealEar evaluation with FM system

8. Press [MENU] to enter the SPL Menu.

9. Select COMPOSITE for AIDED CURVE 1 and AIDED CURVE 2 using the arrow keys.

10. Press [MENU] to return to the SPL Test Screen.

11. If necessary, use [∧] to select CRV 1.

12. Adjust the source level of CRV 1 to 65 dB SPL using [<, >].

13. Press [START/STOP] to begin the measurement.

14. When the measurement has stabilized, press [START/STOP] again to stop it.

15. This curve will be referred to as the Real-Ear Hearing Aid Response or RHA65. See Figure 2.2.1.

2.2.2 Test FM system with typical input — RFM80

1. Set up and level the FM system according to Section 2.1.2. The environmental microphone on the FM receiver should be off.

2. Use [∨] to select CRV 2.

3. Use [<, >] to adjust the amplitude of CRV 2 to 80 dB SPL.

Figure 2.2.2

Comparison of RHA65 (CRV 1) and RFM80 (CRV 2)

4. Press [START/STOP] to begin the measurement.

5. When the measurement has stabilized, press [START/STOP] again to stop it.

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Testing FM Systems with FONIX 6500-CX Analyzers

6. This curve will be referred to as the Real-Ear FM Response or RFM80. See Figure

2.2.2.

7. Compare RHA65 (CRV 1) to RFM80 (CRV 2). If you have a child with a mild to moderate hearing loss (less than 80 dB HL), the output of the two curves should be within 5 dB of each other. If you have a child with a severe to profound loss (greater than 80 dB HL), the output of EFM80 should be 7-10 dB higher than the output of EHA65.

To obtain a better match, first adjust the FM volume control. As a last resort, adjust the settings on the hearing aid and inform the teacher, parents, and therapists that when the FM system is used, the settings on the hearing aid must be changed for optimum performance.

2.2.3 Test aid with high-level input—RHA90

1. If you followed the instructions from Sections 2.2.1 and 2.2.2, you will be in the SPL Test Screen.

2. Press [MENU].

3. Select PT_BURST for AIDED CURVE 1 and AIDED CURVE 2.

4. Press [MENU] to return to the SPL Test Screen.

5. Follow the instructions found in Section 2.1.1 to set the client up for a real-ear hearing aid measurement and level the sound field.

Figure 2.2.3

RHA90-real-ear saturation response of the hearing aid

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Section 2: RealEar evaluation with FM system

6. If necessary, use [∨, ∧] to select CRV 1.

7. Use [>] to adjust the source level to 90 dB SPL.

8. Press [START/STOP] to take the measurement.

9. This curve will be referred to as the Real-Ear Hearing Aid Saturation Response or RHA90. See Figure 2.2.3.

2.2.4 Test FM system with high-level input—RFM90

1. Set up the FM system according to Section 2.2.2. The environmental microphone should be off.

2. Use [∨] to select CRV 2.

3. Use [>] to adjust the amplitude of CRV 2 to 90 dB SPL.

4. Press [START/STOP] to take measurement.

5. This curve will be referred to as the Real-Ear FM Saturation Response or RFM90.

6. Compare RHA90 (CRV 1) and RFM90 (CRV 2). If necessary, adjust the FM volume control to obtain a better match. As a last resort, adjust the settings of the hearing aid. If this must be done, the teacher, parents, and therapists must be made aware that when the FM system is used, the settings on the hearing aid must be changed for optimum performances. See Figure 2.2.4.

Figure 2.2.4

Comparison of RHA90 (CRV 1) and RFM90 (CRV 2)

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Testing FM Systems with FONIX 6500-CX Analyzers

2.3 Testing FM+ENV

This section contains a description of the different real-ear measurements of FM systems when the client primarily uses the system with the environmental microphone added to the FM signal (FM+ENV mode). These measurements are:

• Response of aid with 65 dB SPL signal at 1 kHz

• Response of FM transmitter/receiver with 65 dB SPL signal at 1 kHz

• Verify increase of FM transmitter/receiver when signal level is increased to 80 dB SPL.

• RHA65: typical real-ear response of the aid

• RFE80: typical real-ear response of the FM transmitter/receiver

• REF65: typical real-ear response of environmental microphone

• RHA90: saturation real-ear response of the aid

• RFE90: saturation real-ear response of the FM transmitter/receiver

• REF90: saturation real-ear response of environmental microphone

2.3.1 Single frequency output of hearing aid

1. Press [RESET] on the main module of the 6500-CX.

2. Enter Real-ear Mode by pressing [START/STOP] on the remote module. This will open the Insertion Gain Screen.

3. Set up the client for a normal real-ear measurement as described in Section 2.1.1. Make sure to level the sound field speaker.

Figure 2.3.1

Hearing aid output with 65 dB SPL signal at 1 kHz

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Section 2: RealEar evaluation with FM system

4. Press [MENU].

5. Highlight MODE with [∨, ∧].

6. Select PURE TONE with [<, >].

7. Highlight GAIN(G)/SPL with [∨].

8. Select G/REF OFF with [<, >].

9. Press [MENU] to return to the Insertion Gain Screen.

10. If necessary, use [<, >] to set the FREQUENCY to 1000 Hz in the CURRENT STATUS box.

11. Press [START/STOP] to begin a single tone continuous measurement.

12. Use [∨, ∧] to adjust signal level to 65 dB.

13. Record the MIC OUT reading in the CURRENT STATUS box. This is the “Hearing Aid Output” at 65 dB SPL at 1000 Hz. See Figure 2.3.1.

14. Press [START/STOP] to stop the measurement.

2.3.2 Single frequency response of FM mic at 65 dB SPL

1. Set up the FM system as described in Section 2.1.2. Set the FM to receive FM+ENV.

2. Press [START/STOP] to begin a single tone continuous measurement.

3. Note the MIC OUT reading in the CURRENT STATUS box. This is the “FM Output.”

4. Adjust the FM receiver volume control so that the FM Output matches the Hearing Aid Output found in Section 2.3.1. Now the gain of the hearing aid and the FM system have been matched.

5. Press [START/STOP] to stop the measurement.

2.3.3 Verify increase in signal level

1. Press [START/STOP] to begin a single tone continuous measurement.

2. Use [∧] to adjust the signal to 80 dB SPL.

3. Note the AID OUT on the left side of the screen, below the graph. This is the FM Output.

4. Compare the Hearing Aid Output (from Section 2.3.1) and the FM Output and adjust the FM receiver volume control if necessary according to the following:

If the increase is:

• 10 dB, no further adjustments are needed.

• 15 dB, reduce the FM receiver volume control so that the FM Output falls by 5 dB.

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Testing FM Systems with FONIX 6500-CX Analyzers

• 5 dB, increase the FM receiver volume control so that the FM Output increases by 7 or 8 dB.

• 0 dB, the FM transmitter may have a very low compression threshold, so increase the FM receiver volume control to provide a 5 dB increase in output.

2.3.4 Test aid with typical input – RHA65

1. Set the client and hearing aid up for a real-ear test, as described in Section 2.1.1. Make sure to level the sound field speaker.

2. Press [MENU] to enter the Quik-Probe II Menu.

2. Highlight CREATE TARGET using [∨, ∧].

3. Select SPL TARGET using [<, >].

4. Press [START/STOP] twice. This will open the SPL Test Screen.

Figure 2.3.4

RHA-real-ear response of hearing aid

5. Make sure that the bottom left corner of your screen says MANUAL. If it says AUTO, press [UNAIDED] to change it to MANUAL.

6. Press [MENU].

7. Select COMPOSITE for AIDED CURVE 1, AIDED CURVE 2, and AIDED CURVE 3.

8. Press [MENU] to return to the SPL Test Screen.

9. If necessary, use [∧] to select CRV 1.

10. Adjust the source level of CRV 1 to 65 dB SPL using [<, >].

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Section 2: RealEar evaluation with FM system

11. Press [START/STOP] to begin the measurement and again when a stable response is observed..

12. This curve will be referred to as the Real-Ear Hearing Aid Response or RHA65. See Figure 2.3.4.

2.3.5 Test FM system with typical input – RFM80

1. Set up the FM system following the instructions found in Section 2.3.1. Set the FM receiver for FM+ENV. Make sure to level the sound field speaker.

2. Use [∨] to select CRV 2.

3. Use [<, >] to adjust the amplitude of CRV 2 to 80 dB SPL.

4. Press [START/STOP] to begin measurement. Press it again once a stable response is observed.

5. This curve will be referred to as RFE80 or the Real-Ear FM and Environmental Response with 80 dB SPL input delivered to the FM microphone.

6. Compare RHA65 (CRV 1) to RFM80 (CRV 2) and confirm that the desired FM advantage of 7-10 dB is maintained over the 500 Hz to 2000 Hz frequency range, as shown in Figure 2.3.5. Further adjustments may be made if necessary.

Figure 2.3.5

Comparison of RHA65 (CRV 1) and RFE80 (CRV 2)

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Testing FM Systems with FONIX 6500-CX Analyzers

2.3.6 Test environmental mic with typical input—REF65

1. Set up the environmental microphone for testing as described in Section 2.1.3. Make sure to level the sound field speaker.

2. Press [∨] to select CRV 3.

3. Press [<, >] to select a source level of 65 dB SPL.

4. Press [START/STOP] to start the measurement and again once the measurement has stabilized.

5. This measurement will be referred to as REF65 or the Real-Ear FM and Environmental Response with 65 dB SPL input delivered to the environmental microphone.

6. Compare RHA65 (CRV 1) to RFE80 (CRV 2) and REF65 (CRV 3). RHA65 and REF65 should be similar while RFE80 should give a 7-10 dB advantage. See Figure 2.3.6.

Figure 2.3.6

Comparison of RHA65 (CRV 1),

RFE80 (CRV 2), and REF65 (CRV 3)

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Section 2: RealEar evaluation with FM system

2.3.7 Test aid with high-level input—RHA90

1. Set the client and hearing aid up for real-ear testing as described in Section 2.3.1. Make sure to level the sound field speaker.

2. From the SPL Test Screen, press [MENU].

3. Select PT_BURST for AIDED CURVE 1, AIDED CURVE 2, and AIDED CURVE 3.

4. Press [MENU] to return to the SPL Test Screen.

5. Press [∧] to select CRV 1.

6. Use [>] to adjust the source level to 90 dB SPL.

7. Press [START/STOP] to take measurement.

8. This curve will be referred to as the Real-Ear Hearing Aid Saturation Response or RHA90. See Figure 2.3.7.

Figure 2.3.7

RHA90-Real-Ear Saturation Response of the Aid

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Testing FM Systems with FONIX 6500-CX Analyzers

2.3.8 Test FM system with high-level input—RFE90

1. Set up the FM system according to Section 2.1.2.

2. Use [∨] to select CRV 2.

3. Use [>] to adjust the amplitude of CRV 2 to 90 dB SPL.

4. Press [START/STOP] to take measurement.

5. This curve will be referred to as RFE90 or the Real-Ear FM and Environmental Response with 90 dB SPL input delivered to the FM microphone. See Figure 2.3.8.

6. If RFM90 is greater than 5 dB above RHA90, adjust the FM controls to obtain a better match. As a last resort, adjust the settings on the hearing aid. If this must be done, the teacher, parents, and therapists must be made aware that when the FM system is used, the settings on the hearing aid must be changed for optimum performances. For mild to moderate losses it is usually acceptable if the RFM90 is 5-10 dB below RHA90.

Figure 2.3.8

Comparison of RHA90 (CRV 1) and RFE90 (CRV 2)

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57Section 2: RealEar evaluation with FM system

2.3.9 Test environmental mic with high-level input—REF90

1. Set up the equipment as described in Section 2.1.3 of this guide for real-ear testing of environmental microphones. Make sure to level the sound field speaker.

2. Press [∨] to select CRV 3.

3. Use [<, >] to adjust the source level of CRV 3 to 90 dB SPL.

4. Press [START/STOP] to take the measurement.

5. This response curve will be referred to as REF90, or the Real-Ear FM and Environmental Response with 90 dB SPL input to the environmental microphone. See Figure 2.3.9.

6. Compare RHA90 (CRV 1), RFE90 (CRV 2), and REF90 (CRV 3). All three responses should match.

Figure 2.3.9

Comparison of RHA90 (CRV 1),

RFE90 (CRV 2), and REF90 (CRV 3)

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Testing FM Systems with FONIX 6500-CX Analyzers

Glossary:

Coupler Measurement Labels

EHA65 Electroacoustic Hearing Aid Response with 65 dB SPL input

EFM80 Electroacoustic FM Response with 80 dB SPL input

EHA90 Electroacoustic Hearing Aid Saturation Response with 90 dB SPL input

EFM90 Electroacoustic FM Saturation Response with 90 dB SPL input

EFE80 Electroacoustic FM and Environmental Response with 80 dB SPL input to the

FM microphone

EEF65 Electroacoustic FM and Environmental Response with 65 dB SPL input to the

Environmental microphone

EFE90 Electroacoustic FM and Environmental Response with 90 dB SPL input to the

FM microphone

EEF90 Electroacoustic FM and Environmental Response with 90 dB SPL input to the

Environmental microphone

Real-Ear Measurement Labels

RHA65 Real-Ear Hearing Aid Response with 65 dB SPL input

RFM80 Real-Ear FM Response with 80 dB SPL input

RHA90 Real-Ear Hearing Aid Saturation Response with 90 dB SPL input

RFM90 Real-Ear FM Saturation Response with 90 dB SPL input

RFE80 Real-Ear FM and Environmental Response with 80 dB SPL input to the FM

microphone

REF65 Real-Ear FM and Environmental Response with 65 dB SPL input to the

Environmental microphone

RFE90 Real-Ear FM and Environmental Response with 90 dB SPL input to the FM

microphone

REF90 Real-Ear FM and Environmental Response with 90 dB SPL input to the

Environmental microphone

Page 62

Acknowledgments and References

Frye Electronics, Inc. gratefully acknowledges the personal assistance of Dawna Lewis and Pat Stelmachowicz of the Boys Town National Research Hospital, Richard Seewald, Shane Moodie, and Sheila Sinclair of the University of Western Ontario, and Cynthia Compton of Gallaudet University. The procedures given in this guide do not necessarily reflect the recommendations of these audiologists; Frye Electronics, Inc. is solely responsible for the contents of this guide. Frye Electronics, Inc. also thanks Phonak, Telex, Comtek, and Phonic Ear for providing the equipment used in developing this guide.

This guide was revised in January, 2003 with considerable assistance from Dr. Linda Thibodeau of the Advanced Hearing Research Center, University of Texas at Dallas.

For further study of methods and procedures for testing FM systems and auditory trainers, the reader is referred to the following resources:

American Speech-Language-Hearing Association. (1999, In Press) Guidelines for Fitting and

Monitoring FM Systems.

Cornelisse LE, Gagné J-P, and Seewald RC. Long-term average speech spectrum at the chest-

level microphone location. Journal of Speech Language Pathology and Audiology (Canada), Vol. 15., No. 3, pp. 7-12, 1991.

Lewis DE. FM systems and assistive devices: selection and evaluation. In Pediatric

Amplification, Proceedings of the 1991 National Conference, J. Feigin and P. Stelmachowicz

(eds.), Boys Town National Research Hospital, Omaha, NE, 1991.

Lewis DE, Feigin JA, Karasek A, and Stelmachowicz PG. Evaluation and assessment of FM

systems. Ear and Hearing, 12, pp. 268-280, 1991.

Seewald RC and Moodie KS. Electroacoustic considerations. In FM Auditory Training

Systems, M. Ross (ed.), Chapter 4, York Press,Timonium, MD, 1992.

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Testing FM Systems with FONIX 6500-CX Analyzers

Frye FONIX 6500-CX Workbook

Specifications and Main Features

Frequently Asked Questions

User Manual