13_ANSI Overview Flashcards
What types of things are shown on a hearing aid specification sheet?
- fitting range
- features (e.g sound cleaning, audibility, wireless connectivity, filter options…)
- technical data (2cc coupler, frequency range, full-on gain, THD…)
What two organizations determine hearing aid standards?
American National Standards Institute (ANSI)
International Electrotechnical Commission (IEC)
What does standardized testing ensure?
- Uniform level and high quality of methods, equipment, and procedures
- Reproducibility free from “how”, “when”, and “by whom”
(ensures continuity and fairness in comparison)
How are ANSI tests run?
- 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)
Which 3 frequencies is the average OSPL-90 calculated across?
1000, 1600, and 2500 Hz
In Full-on Gain Test Mode, the gain and volume control are both set to ____
Max
What is the OSPL-90?
The Output Sound Pressure Level with 90 dB input level
What is the HFA-OSPL90?
The average output at the high frequency average (HFA) frequencies (1000, 1600, 2500 Hz)
What is Special Purpose Average (SPA)?
When the manufacturer has used other frequencies than the typical ones used for HFA-OSPL90, and so you need to do your own calculations
What is FOG?
Full-on Gain
- gain with input at 50 dB SPL
What is HFA-FOG?
High frequency average full on gain
- FOG averaged across the HFA frequencies
- no curve for HFA-FOG
What is RTS? What is the goal of RTS?
Reference Test Setting
Goal: to choose a gain setting that does not saturate the HA amplifier for average speech input
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
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
What is HFA-RTS gain?
The average gain across the HFA frequencies
What is the frequency range in RTS Mode?
The range between the lowest and highest frequency at which the frequency response curve is 20 dB below its HFA value
What are the THD frequencies and levels when measured at the RTS?
500 Hz at 70 dB SPL
800 Hz at 70 dB SPL
1600 Hz at 65 dB SPL
In the THD equation:
%THD = sqrt (p2sq + p3sq…/p1sq) x 100
what do P1 and P2 represent, and in what units?
P1 = pressure for the fundamental
P2, P3… = pressures for the harmonics
All in Pa (since they are pressures)
A typical good hearing aid THD is around ___ or ___%. Anything greater than ___% is really bad.
1 or 2%
>10% = bad
What does EIN stand for?
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
What is a typical EIN range?
20 - 35 dB SPL
Name 2 reasons you might get a high EIN result for a hearing aid?
1) Hearing aid is faulty b/c internal circuit is damaged and requires repair
2) Improper seal or noisy environment during testing
Can you do a battery current drain test using a USB to HiPro connector?
No; needs to be wireless so that you can use the battery pill
What are the 3 parameters for conducting a battery current drain test (e.g. setting, frequency, etc)?
RTS position
1000 Hz
65 dB SPL
How do you set up for an induction coil response test?
Hearing aid in RTS
Input set to T or telecoil
Hearing aid positioned on a telephone magnetic field simulator
What does HFA-SPLITS stand for?
High Frequency Average Sound Pressure Level for Induction Telephone Simulator
During an HFA-SPLITS test, the gain is set to RTS and the AGC is set for _____ (min/max) effect
Minimum
What might a jagged frequency response indicate during an ANSI test?
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
What is one thing you should double check, if you get an unusual frequency response during an ANSI test?
That the right coupler is being used, and is connected correctly to the hearing aid
Name 2 ANSI measures that use the FOG setting
OSPL90 and HFA-FOG
Name 5 ANSI measures that use the RTS mode
HFA-RTS Frequency Range THD EIN Telecoil response
What are the pros and cons of quality control measures?
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)
