Bose T5 Service Manual page 22

PASS/FAIL Criteria. Words should be heard
clearly and be recognizable.
3.6 Talk-through Compressor Operation.
Listen to the audio signal. Move the gain
switch to the +15dB position. Wait for the
sound of words to stablilize before listening
to a minimum of four words from the audio
signal.
PASS/FAIL Criteria. The level of sound
heard through the talk-through must not
increase dramatically after the sound of
the words stabilizes. If verification is
needed compare ambient sound at
increased gain level to sound heard
through the talk-through system.
If headset's compressor takes longer than
five words to stabilize, it is a failure.
4. Talk-through Operation, Active Noise
Reduction (ANR) ON, Quiet Environment
This test verifies proper Talk-through
balance, intelligibility and compressor opera-
tion.
Set-Up 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
4.1 Talk-through Gain. Listen to the
Talk-through background noise in a quiet
environment. Exercise the TT Switch to
+5dB and +10dB positions respectively.
PASS/FAIL Criteria. The noise of the TT
circuit should increase for both earcups at
the +5dB position, and then increase for
both earcups again at the +10dB position.
The headset should not oscillate with either
+5 or +10dB gain.
TEST PROCEDURES
22
5. Talk-Through Operation, ANR ON
This test is to verify Talk- through balance,
and intelligibility.
Set-Up 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 - On
• Sound Booth Noise Switch - Off
• Sound Booth Audio Switch - Off
5.1 Talk-through Balance. Listen to the
audio signal while facing the signal source.
Block the left talk through microphone with
your hand and listen to the audio signal
through the right.
5.2 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.
5.3 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.
5.4 Talk-through Gain Switching. Exercise
the TT Rotary switch to the 5dB position.
PASS/FAIL Criteria. Words should be
heard clearly, and should be recognizable.
5.5 Talk-through Compressor Operation.
Listen to the audio signal. Switch the gain
switch to +15 dB. Wait for the sound of
the words to stabilize before listening to a
minimum of four words from the audio
signal.