Audioscan Axiom - Manual (Page 48)

Axiom ® User's Guide Version 1.8  May 2015
AGC tests.
ANSI 1996 Linear and AGC tests
5. Refer to Test Box Measures – Setup, Coupling the hearing instrument and Positioning the hearing instrument
to prepare the instrument for testing.
6. Click , then click [Linear] or [AGC] on the Test box menu.
7. Click [Start test] and follow the test setup instructions which are presented.
8. Turn the instrument ON.
9. Set the gain control (manual or programmable) to maximum with all other controls set to provide the widest
frequency response, greatest gain and highest maximum output. AGC controls and/or programmable
parameters should be set as designated by the manufacturer.
10. Click to run the test or to abort the test. Note that, if required, the Axiom will pause during the
test to request that the volume control be adjusted to the Reference Test Position (RTP). Open the test box if
necessary and, without moving the hearing instrument, adjust the user gain control until the large vertical
arrow on the screen prompt disappears. Click
to resume the test.
If you are unsure which test sequence to run, try [AGC] first. If attack and release times are all near zero, the
instrument is probably linear.
ANSI 2003 Linear and AGC tests
1. Refer to Test Box Measures – Setup, Coupling the hearing instrument and Positioning the hearing instrument
to prepare the instrument for testing.
2. Click , then click [Linear] or [AGC] on the Test box menu.
3. Click [Start test] and follow the test setup instructions which are presented.
4. Turn the instrument ON.
5. Set the gain control (manual or programmable) to maximum with all other controls set to provide the widest
frequency response, greatest gain and highest maximum output. AGC controls and/or programmable
parameters should be set to minimize AGC action (AGC off or threshold high, compression ratio close to 1).
6. Click to run the test or to abort the test. Note that, if required, the Axiom will pause during the
test to request that the gain control be adjusted to the Reference Test Setting (RTS). If necessary, open the
HIT chamber and, without moving the hearing instrument, adjust the gain control until the large vertical
arrow on the screen prompt disappears. Click
to resume the test.
During the AGC test, the Axiom will pause to request that AGC controls or programmable parameters be set for
maximum AGC effect. If the manufacturer does not provide settings to produce maximum AGC effect, use
settings that result in the highest gain for soft sounds and the lowest gain for loud sounds. This will typically
result in the lowest compression threshold, a flat I/O curve and the longest attack/release times. These are not
'typical' characteristics but indicate the adjustment range possible for these parameters.
If you are unsure which test sequence to run, try [AGC] first. If attack and release times are all near zero, the
instrument is probably linear.
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