13_ANSI Overview

Question 1

What types of things are shown on a hearing aid specification sheet?

Answer 1

• fitting range
• features (e.g sound cleaning, audibility, wireless connectivity, filter options…)
• technical data (2cc coupler, frequency range, full-on gain, THD…)

Question 2

What two organizations determine hearing aid standards?

Answer 2

American National Standards Institute (ANSI)

International Electrotechnical Commission (IEC)

Question 3

What does standardized testing ensure?

Answer 3

• Uniform level and high quality of methods, equipment, and procedures
• Reproducibility free from “how”, “when”, and “by whom”
  (ensures continuity and fairness in comparison)

Question 4

How are ANSI tests run?

Answer 4

• attach HA to fitting software
• choose appropriate coupler (HA-1, HA-2; all tests conducted with 2cc)
• orient HA properly in test box
• choose appropriate programming interface
• use fitting software to set HA in “test” mode
• insert battery pill connector (for battery drain measurement)

Question 5

Which 3 frequencies is the average OSPL-90 calculated across?

Answer 5

1000, 1600, and 2500 Hz

Question 6

In Full-on Gain Test Mode, the gain and volume control are both set to ____

Answer 6

Max

Question 7

What is the OSPL-90?

Answer 7

The Output Sound Pressure Level with 90 dB input level

Question 8

What is the HFA-OSPL90?

Answer 8

The average output at the high frequency average (HFA) frequencies (1000, 1600, 2500 Hz)

Question 9

What is Special Purpose Average (SPA)?

Answer 9

When the manufacturer has used other frequencies than the typical ones used for HFA-OSPL90, and so you need to do your own calculations

Question 10

What is FOG?

Answer 10

Full-on Gain

- gain with input at 50 dB SPL

Question 11

What is HFA-FOG?

Answer 11

High frequency average full on gain

• FOG averaged across the HFA frequencies
• no curve for HFA-FOG

Question 12

What is RTS? What is the goal of RTS?

Answer 12

Reference Test Setting

Goal: to choose a gain setting that does not saturate the HA amplifier for average speech input

Question 13

The RTS is the setting of the ____ control to produce an _______ with a ___ dB input SPL that is within 1.5 dB of the HFA OSPL90 minus ____ dB

Answer 13

Since average speech level at 1m is about 65 dB SPL, add 12 dB for peaks = 77 dB SPL, so…

The RTS is the setting of the gain control to produce an HFA gain with a 60 dB input SPL that is within 1.5 dB of the HFA OSPL90 minus 77 dB

Question 14

What is HFA-RTS gain?

Answer 14

The average gain across the HFA frequencies

Question 15

What is the frequency range in RTS Mode?

Answer 15

The range between the lowest and highest frequency at which the frequency response curve is 20 dB below its HFA value

Question 16

What are the THD frequencies and levels when measured at the RTS?

Answer 16

500 Hz at 70 dB SPL
800 Hz at 70 dB SPL
1600 Hz at 65 dB SPL

Question 17

In the THD equation:

%THD = sqrt (p2sq + p3sq…/p1sq) x 100

what do P1 and P2 represent, and in what units?

Answer 17

P1 = pressure for the fundamental
P2, P3… = pressures for the harmonics

All in Pa (since they are pressures)

Question 18

A typical good hearing aid THD is around ___ or ___%. Anything greater than ___% is really bad.

Answer 18

1 or 2%

>10% = bad

Question 19

What does EIN stand for?

Answer 19

Equivalent Input Noise = (coupler output with no input signal) - (HFA gain for a 50 dB input signal)

It is a measure of the internal noise generated by the HA, including thermal, electronic, and ambient fluctuations

Question 20

What is a typical EIN range?

Answer 20

20 - 35 dB SPL

Question 21

Name 2 reasons you might get a high EIN result for a hearing aid?

Answer 21

1) Hearing aid is faulty b/c internal circuit is damaged and requires repair
2) Improper seal or noisy environment during testing

Question 22

Can you do a battery current drain test using a USB to HiPro connector?

Answer 22

No; needs to be wireless so that you can use the battery pill

Question 23

What are the 3 parameters for conducting a battery current drain test (e.g. setting, frequency, etc)?

Answer 23

RTS position
1000 Hz
65 dB SPL

Question 24

How do you set up for an induction coil response test?

Answer 24

Hearing aid in RTS
Input set to T or telecoil
Hearing aid positioned on a telephone magnetic field simulator

Question 25

What does HFA-SPLITS stand for?

Answer 25

High Frequency Average Sound Pressure Level for Induction Telephone Simulator

Question 26

During an HFA-SPLITS test, the gain is set to RTS and the AGC is set for _____ (min/max) effect

Answer 26

Minimum

Question 27

What might a jagged frequency response indicate during an ANSI test?

Answer 27

Distortion within the HA

• distortion numbers would likely also be high (>10%)
• would need to send HA back to manufacturer for repair, along with details of the ANSI test

Question 28

What is one thing you should double check, if you get an unusual frequency response during an ANSI test?

Answer 28

That the right coupler is being used, and is connected correctly to the hearing aid

Question 29

Name 2 ANSI measures that use the FOG setting

Answer 29

OSPL90 and HFA-FOG

Question 30

Name 5 ANSI measures that use the RTS mode

Answer 30

HFA-RTS
Frequency Range
THD
EIN
Telecoil response

Question 31

What are the pros and cons of quality control measures?

Answer 31

Pros:
Great way to find out if HA performing correctly/verifications

Limitations:
No information on perception
Vents are sealed
Test mode (not real world settings)
Automatic features not tested/part of quality control measures (need additional tests)