Introduction to the 8000 Hearing Aid Test System By: Kristina Frye Frye Electronics, Inc.
Outline • Coupler Measurements • Coupler Directional • ANSI/IEC • Coupler Multicurve • Advanced Coupler: Enhanced DSP, Attack & Release, I/O, Battery Current
Coupler Directional F3 – Advanced Coupler F5 – Coupler Directional
Directional Measurements Polar Plot Difference (0° vs 135°)
Simultaneous, Manual, and Auto Modes • In Simultaneous Mode, five polar plot curves are measured simultaneously • A Composite source signal is used to take the measurements. The response at specified frequencies is graphed • In Manual Mode, the user selects the curve to measure. A Puretone signal at the user specified frequency or a Composite source is used. • In Auto Mode, the user can pre-save manual measurements and run curves automatically
Basic Coupler Measurements Coupler Multicurve — F1 ANSI 03 — F4
ANSI 03 Settings Aid type Telecoil Frequencies Choose ear
ANSI 03 Results Max OSPL90-HFA OSPL90 Distortion FOG EIN Response curve Telecoil Battery current Attack & Release I/O curves Telecoil
Coupler Multicurve Features • Realistic frequency response measurements • Variety of signal types: Composite, Digital Speech, Pure-tone sweeps • Display 10 different curves simultaneously • Switch back and forth between gain and output. All curves translated.
Coupler Screen Operation Amplitude Choose Ear Select Curve Source Type
Example 50 dB 60 dB 70 dB 80 dB
Testing Digital Aids • Digital Speech • Type of Composite signal • Modulated to allow testing of noise reducing digital aids • Used with ANSI or ICRA speech spectra
Example of digital aid test Digital Speech Composite
Testing Open Fit Hearing Aids • The Open Fit Coupler was designed to • Provide a realistic response for open fit hearing aids. • Provide an easy mechanism for attaching an open fit hearing aid to a coupler • The Open Fit Coupler is a non-standard sized coupler not designed to test to manufacturing specifications
Attaching the Open Fit Coupler CRV 1 = Open Fit Coupler CRV 2 = HA-1 CRV 3 = HA-2 w/attachment CRV 4 = KEMAR
Coupler Automation • Set up own test sequence • Select signal type for each curve • Select signal amplitude for each curve • Add any desired pauses in test sequence • Save and auto load test sequence
Programming Auto Mode Help window w/instructions F6 — Program Mode F5 — Source Type Amplitude START Advance to next curve without pause Advance to next curve with pause STOP
Example of Auto Test Digital Speech @ 50, 65, 80 dB Pure-tone sweep @ 90 dB F6 — Fully Automatic mode
Saving and Loading Settings Automatically load saved curve group and put analyzer in Auto Mode
Troubleshooter Profiler Great for baseline testing… save time!
Advanced Coupler • Battery Current [F1] • Coupler I/O [F2] • Attack & Release [F3] • Enhanced DSP [F4] Function key operations available in the Advanced Coupler Navigation Screen
Battery Current Screen • Measure Battery Current as a function of frequency • Measure Battery Current as a function of amplitude • Estimate battery life of hearing aid
Coupler I/O Test Results Test Results Frequency F5: Source Type
Attack & Release Test Screen • Visual time graph of Attack and Release tests • Scale graphs independently to zoom in on results • Use Composite or Pure-tone • Choose any frequency from 200-8000 Hz in 100 Hz intervals • Customize amplitudes used in tests
Attack & Release Results Frequency F5: Source type F6 & F7: Change graph scales
Enhanced DSP • Designed to measure the "group delay" of a DSP aid. In other words, the actual digital processing time of a hearing aid. • 0 ms for analog aids • 1-12 ms for DSP • Great way to check if aid is analog or DSP • Also tests the "phase" of a hearing aid. This is useful for binaural fittings. Are the aids working together?
Technical Details: Group Delay An impulse signal is delivered to the hearing aid. The time of the maximum peak of the response is considered the group delay. The 7000 system delay is subtracted from this value to obtain the final measurement.
Technical Details: Phase One pulse of a 1000 Hz cosine signal is delivered to the aid. This signal is 1 msec long. The first 20 msec of the aid's response to the signal is displayed in graphical format.
Example Group Delay Phase