Bose T5 Service Manual page 21

1. Active Noise Reduction (ANR) Operation,
Quiet Environment
Setup Conditions:
•
Talk Through (TT) swith - OFF
• Power supply input - 3.0 Volts
(2 AA batteries) in control module
•
Headset microphone switch - OFF
•
Headset battery ANR switch - OFF
1.1 In a quiet environment, listen to the ANR
operation as you stand still. Ensure that the
earcups are properly seated on your head.
1.2 Slowly compress the cups against your
head with your hands. Move the earcups with
your hands to simulate rapid head and jaw
movement.
1.3 Lift one of the earcups off of the ear
slightly at the back of the jaw to create a
small air leak. Listen for overload or instabil-
ity conditions. Perform this step for the other
earcup.
PASS/FAIL Criteria. Overload or instability
should not be heard under any test condi-
tions. When creating a leak in the back of the
jaw, short term (less than 1 second) instabil-
ity is allowed. If the instability is sustainable
by holding the earcup in the position where
the instability was heard, the headset has
failed this test.
2. Active Noise Reduction (ANR) Operation,
Loud Environment
Setup Conditions:
• Talk Through (TT) swith - Off
• Power supply input - 3.0 Volts
(2 AA batteries) in control module
• Headset microphone switch - Off
• Headset battery ANR switch - Off
• Sound Booth Noise Switch - On
• Sound Booth Audio Switch - Off
2.1 Listen to ANR operation as you stand
still. Ensure that the earcups are sealed to
your head.
TEST PROCEDURES
21
2.2 Slowly compress the cups against the
head with your hands. Move the earcups
with your hands to simulate rapid head and
jaw movement. Listen for overload or
instability conditions.
PASS/FAIL Criteria. ANR Operation should
be apparent. Overload or instability should
not be heard under any test conditions.
3. Talk -Through (TT) Operation, ANR OFF
This test is to verify talk-through balance
and intelligibility.
Setup Conditions:
•
TT switch - Talk-through ON 0dB
•
Power supply input - 3.0 Volts
(2 AA Batteries) in Control Module
• Headset Microphone switch - Off
• Headset Battery ANR Switch - Off
•
Sound Booth Noise Switch - Off
•
Sound Booth Audio Switch - On
3.1 Talk-through Balance - Listen to the
audio signal while facing the signal source.
3.2 Block the left talk through microphone
with your hand and listen to the audio
signal through the right.
3.3 Uncover the left side and cover the
right side. Listen to the audio signal through
the left side.
PASS/FAIL Criteria. The audio signal
should be heard at the same level in both
sides of the headset and there should be
no noticeable background noise.
3.4 Talk-through Intelligibility. Listen to a
minimum of four words from the audio
signal.
PASS/FAIL Criteria. Words should be
heard clearly, and should be recognizable.
3.5 Talk-through Gain Switching. Move the
TT rotary switch to the 5dB position.