0611
Verifit User’s Guide Version 2.8
Page 40
8.2
ANSI S3.22-1996 facts
FastFacts 8.2: ANSI S3.22-1996 facts
8.3
ANSI S3.22-2003 facts
FastFacts 8.3: ANSI S3.22-2003 facts
The Verifit performs selected hearing instrument tests in accordance with ANSI
S3.22-1996. This standard expresses some outputs and gains as High Frequency
Average (HFA) values. The HFA is the average of values at 1000, 1600 and 2500
Hz. If a hearing aid meets certain conditions, the manufacturer may choose other
averaging frequencies called Special Purpose Average (SPA) frequencies. The
current averaging frequencies are indicated explicitly on test results where space
permits and also appear as tick marks on the frequency axis of graphs. To change
the averaging frequencies, see
7.7: ANSI test frequencies
.
This standard also requires some tests with the gain control full on and some with
the gain control in the Reference Test Position (RTP). This requirement applies to
both Linear and AGC aids that have a HFA (or SPA) full-on gain greater than the
HFA (or SPA) OSPL90 minus 77 dB. Otherwise the RTP is full on. If required, the
Verifit will pause in its testing and guide you in setting the gain control to the RTP.
All other controls on the hearing instrument should be set to provide the widest
frequency response, the greatest gain and the highest maximum output. AGC
controls and/or programmable parameters should be set as designated by the
manufacturer.
At full-on gain the
[Linear]
and
[AGC]
test sequences provide a curve of OSPL90
(Output Sound Pressure Level for a 90 dB input SPL), the HFA (or SPA) and peak
value of this curve, the frequency of the peak and the HFA (or SPA) gain for a 50
dB input SPL.
With the gain control at RTP, these sequences also provide a frequency response
curve with an input SPL of 60 dB (Linear) or 50 dB (AGC), the HFA (or SPA) gain
for a 60 dB input SPL, the frequency range, battery drain, equivalent input noise,
harmonic distortion, attack and release time (AGC only).
ANSI S3.22-2003 has been designated a recognized standard by the FDA but is
not yet mandatory. Manufacturers may use either version for reporting test data.
The most significant change from the 1996 version is the requirement for the
hearing aid to be set in its most linear mode for the setting of the gain control to
Reference Test Setting (changed from Reference Test Position) and for all tests
except attack and release and input-output (I/O) curves. These two tests are to be
conducted with the AGC function set for maximum effect. The AGC test sequence
will pause to allow AGC to be set prior to measuring attack and release time.
Full-on gain is determined with 50 dB input SPL (60 dB was formerly an option)
and frequency response curves are run at 60 dB SPL for Linear
and
AGC aids.
The OSPL90 curve, the HFA (or SPA) and peak value of this curve, the frequency
of the peak, the HFA (or SPA) full-on gain are determined at full-on gain setting.
The response curve, frequency range, Reference Test Gain, battery drain,
equivalent input noise, distortion, attack and release times are determined at RTS.
These changes result in more consistent values for reference test gain, equivalent
input noise and attack and release time. See
7.6: 1996 or 2003 ANSI standard
,
8.2: ANSI S3.22-1996 facts
and
8.5: ANSI 2003 Linear and AGC tests
.
