iv FONIX FP35 Hearing Aid Analyzer
2.5.1.1 Delay Settings............................................................................35
2.5.1.2 Harmonic Distortion .....................................................................35
2.5.1.3 Noise Reduction.........................................................................36
2.5.1.4 Warble Rates ............................................................................36
2.5.1.5 Adjusting the Signal Skew................................................................37
2.5.1.6 Three-Frequency Averages ..............................................................38
2.5.2 Understanding Composite Signals ..............................................................38
2.5.2.1 Filter Type ...............................................................................39
2.5.2.2 Intermodulation Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.5.2.3 Noise Reduction.........................................................................43
2.5.3 Measuring RMS .................................................................................43
2.5.4 Measuring the RMS of the reference microphone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.5.5 Using the Earphone Jack ........................................................................46
2.5.6 Using Impulse Rejection ........................................................................47
2.5.7 Using an External Speaker or Sound Chamber ..................................................47
2.5.8 Measuring Telecoil ..............................................................................48
2.6 Printing ...............................................................................................50
2.6.1 Choosing the Printer............................................................................50
2.6.2 Adding a Label .................................................................................51
2.6.3 Changing the Thermal Paper ...................................................................52
2.6.4 Fixing Paper Jams ...............................................................................53
2.6.5 Minimizing Fading..............................................................................53
2.6.6. Using an External Printer .......................................................................54
2.7 Display & Data ........................................................................................54
2.7.1 Data Display ....................................................................................54
2.7.2 Curve ID Box ....................................................................................55
Chapter 3: Coupler Measurements
3.1 Coupler Multicurve Display ..........................................................................57
3.2 Leveling the Sound Chamber.........................................................................58
3.2.1 Leveling without the Reference Microphone (Standard) ........................................59
3.2.2 Leveling Using the Reference Microphone .....................................................60
3.2.3 Saving the Leveling Information ................................................................61
3.2.4 Changing the Leveling Source...................................................................61
3.3 Hearing Aid Setup ....................................................................................62
3.3.1 Setting up a BTE ................................................................................62
3.3.2 Setting up an ITE ...............................................................................63
3.3.3 Setting up a Body Aid...........................................................................64
3.4 Frequency Responses ................................................................................64
3.4.1 Running a Test Curve ...........................................................................65
3.4.2 Running a Single Frequency Measurement .....................................................67
3.5 Distortion Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
3.5.1 Measuring Harmonic Distortion.................................................................68
3.5.2 Measuring Intermodulation Distortion..........................................................69
3.5.3 Performing an IM Distortion Sweep .............................................................71
3.5.4 Changing the Frequencies of an IM Distortion Sweep ...........................................72
3.5.5 Turning on/off Impulse Rejection...............................................................72
3.5.6 Using the Reference Microphone...............................................................73
