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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 environ-
mental 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)