Electroacoustic Evaluation of Assistive Listening Devices
EVALUATION OPTIONS
A. Audio-____________________ Checks
B. Electroacoustic Measurements
**Verifying Performance**
Matching FMs to
____________________
C. Real Ear Evaluation
Verifying Performance
____________________ FMs to HAs
D. Behavioral Evaluation
Speech ____________________
Historical
Overview
Rationale for Electroacoustic and ____________________ Ear Verification
Electroacoustic
variations in Direct-input Arrangements
(Thibodeau, 1990)
Electroacoustic
variations in Neckloop Arrangements
(Thibodeau,
McCaffrey, Abrahamson, 1988)
2 FM Systems were evaluated with 12 Hearing Aids
via neckloop arrangements
Current Situation
Standard for the ____________________ Evaluation of ALDs awaiting approval by
ANSI
ASHA Guidelines for Fitting and Monitoring
FM Systems approved by Leg. Council at ASHA, 1999 (Supercede the 1994 Document)
Summary of ASHA 1999 Guidelines
Personnel
Preselection
Management Orientation
Monitoring
Fitting and Adjustment
Electroacoustic
Real
Ear
____________________
Fitting and Adjustment
____________________ Measures
Real Ear Measures
Behavioral Measures
NEW TERMINOLOGY
While in a sea of
strips from the test box
it occurred to me that we needed new
terms
Start Simple
.First
Letter
E for
Electroacoustic Measures
R for ____________________ ear Measures
Then
HA for
Hearing aid
FM for
____________________ system in FM mode
Golden Rule
The most popular ____________________ must have 4 letters,
e.g. CROS, WIPI, REAR, ABLB, RESR
NEW CONVENTIONS
F or FM will always
refer to FM
E will always refer to
Environmental mic unless it is ____________________
then it means
Electroacoustic
You thought REUR, REAR, REIR REOR, and
RESR were too much
.
EHA65
EFM80
EHA90
EFM90
EFE80
EEF65
RHA65
RFM80
RHA90
RFM90
RFE80
REF65
More terminology to clarify
HA & FM
Means
HA coupled to ____________________ system but tested in
FM
only mode
FM+ENV
Means
HA coupled to FM system and tested in
FM+____________________ mode
Electroacoustic Measurements
· 1. Verify FM Performance
Example with body-worn system
2. Match FM to HA Characteristics
Examples with BTE/boot FM
system
1. Verify FM
Performance in a Single Unit
Tests
to perform ____________________ patient arrives for fitting
Ensure
equipment is functioning properly
Check
for ____________________
Check
for Channel Match
Preliminary Setup
1.Level the test box for
Electroacoustic Testing
2. Couple the output of
the FM receiver to the 2cc coupler
3. Set Test Equip to
perform ANSI 96 S3.22 run
Step
1: Set it up similar to testing a body aid
Step 2: Evaluate the FM Receiver set to FM only
Set FM microphone in the test box & FM transmitter and receiver
outside the box
The ____________________is attached to the 2 cc coupler.
2. Verify FM Performance in a Group of FM Units
Consider need to evaluate a GROUP of FM
systems-compare mics, receivers, neckloops, etc.
θ Evaluation of a
Group of FMs for situations where multiple units
are used, the ____________________ across units should be assessed.
A control unit, which is working properly, must be used to provide
constant components while the component of interest is varied.
The following components are evaluated
using ANSI procedures
while holding the remaining components ____________________:
FM Receiver as a ____________________, FM lapel microphones, FM receiver in ____________________
mode, and neckloops.
STEP 1: EVALUATION OF THE FM RECEIVERS WHEN SET TO
RECEIVE THE ____________________ SIGNAL
STEP 2:
EVALUATION OF THE ____________________
MICROPHONES
STEP 3:
EVALUATION OF THE FM RECEIVERS WHEN SET TO
RECEIVE THE ____________________ SIGNAL
STEP 4:EVALUATION OF
THE ____________________
Test both sides of receivers with two
outputs! Dont assume the VCs will be the ____________________.
Note settings completely when collecting
such data
SUMMARY
FM systems should be tested ____________________ in these situations
1) as a single unit for
baseline purposes
2) as a group of units to
check for ____________________ across components