The document discusses standards and regulations for testing hearing aids in the United States, including ANSI and FDA standards. It describes that ANSI standards exist for test methodology using a 2cc coupler, but not for aspects like directional microphones. Hearing aid specialists perform test box analysis to evaluate factors like gain, output, distortion, and noise based on ANSI standards. Measurements are made using standard couplers and involve stimuli signals, microphones, and Fourier analysis to assess the hearing aid's electroacoustic performance.

1. TEST BOX ANALYSIS & ANSI
 In the United States, the manufacture and
dispensing of hearing instruments is
regulated by the Food and Drug
Administration.

2. TEST BOX ANALYSIS & ANSI
 The are no ANSI standards for directional
microphones—only for proper placement
orientation of a directional microphone hearing
instrument during the analysis.
 The is no ANSI standard for battery current
drain. However, it is required that the battery
drain be measured at the reference test gain.

3. TEST BOX ANALYSIS & ANSI
 Hearing instruments must pass certain
performance parameters. These
parameters are defined by the American
National Standards Institute (ANSI).

4. TEST BOX ANALYSIS & ANSI
 The International Electroacoustical
Commission (IEC) is also used to
establish hearing instrument parameters
not defined by ANSI (or required) by the
FDA.

5. TEST BOX ANALYSIS & ANSI
The key difference between ANSI and IEC
is that all electroacoustic measurements
are measured in a 2cc coupler while IEC
measurements are performed in an ear
simulator.

6. TEST BOX ANALYSIS & ANSI
 Hearing Instrument Specialist perform a
test box analysis which meets ANSI
standards—not a manikin or ear simulator.

7. TEST BOX ANALYSIS & ANSI
 Two primary couplers are used in the test box
analysis of the majority of hearing instruments
dispensed in the United States. They are:
1. The HA-1 used primarily for Custom shell hearing
instruments
2. The HA-2 used primarily for BTE style hearing
instruments.

8. TEST BOX ANALYSIS & ANSI
 Test boxes require two microphones to
measure hearing instrument
performance.
1. A control microphone—to monitor the inside
box environment.
2. A reference microphone--to be placed next to
the hearing instrument microphone.

9. TEST BOX ANALYSIS & ANSI
 Many test boxes now use a swept
broadband stimulus signal.
 The frequencies presented are received
by the hearing instrument and the
reference microphone of the test box.

10. TEST BOX ANALYSIS & ANSI
 A Fourier Transform analysis is then made
by the test box to determine the specific
frequencies coming through the hearing
instrument.

11. TEST BOX ANALYSIS & ANSI
High frequency average gain (HFA) and
the frequency range are two important
factors when selecting hearing instruments
for patient/client benefit.
See page 81 of Dillon to summarize these
calculations.

12. TEST BOX ANALYSIS & ANSI
Other test box measures include:
 Gain by frequency response
 Output saturation sound pressure level
(OSPL)
 Harmonic distortion

13. TEST BOX ANALYSIS & ANSI
 Gain by frequency response is measured
with a 60dbSPL input level.
This represents the amount of gain/volume a
hearing instrument posses with a 60dbSPL level
input into it.

14. TEST BOX ANALYSIS & ANSI
Gain of a hearing instrument is important
in providing enough amplification to create
audibility of sound to the patient/client.

15. TEST BOX ANALYSIS & ANSI
 Output Saturation Response Level (OSPL)
Measures the maximum sound pressure level
generated by the hearing instrument. It is
performed with a 90dbSPL input into the hearing
instrument.

16. TEST BOX ANALYSIS & ANSI
The hearing instrument output information
is important for patient comfort with the
electroacoustic performance of the hearing
instrument.

17. TEST BOX ANALYSIS & ANSI
 Equivalent input noise is a measurement
taken of any noise generated by the
hearing instrument itself. The test box
only listens it does not present a signal.
Note: This requires that the testing area be in a
very quiet environment.

18. TEST BOX ANALYSIS & ANSI
 Harmonic distortion is the measurement of
artifacts in the “clear” electroacoustic
performance of a hearing instrument. All
amplifiers have measureable distortion.
However, they must be within the FDA
guidelines for hearing instrument
manufacture.

19. TEST BOX ANALYSIS & ANSI
Harmonic distortion is measured at the
reference test gain setting of the hearing
instrument.
It is then presented with a 70dbSPL pure
tone signal to measure the harmonic
distortion of the hearing instrument.

20. TEST BOX ANALYSIS & ANSI
 Compression measurements are also
made during test box analysis. We will
cover much more regarding compression
next semester.

21. TEST BOX ANALYSIS & ANSI
NOTE: A nice description of methodology
for ANSI test box analysis is found on
pages 186 through 191 in Vonlanthen.