Honeywell Enhanced Xenon 1902H Quick Start Manual page 10

Very Low Beeper (Nighttime Mode)
The following bar code silences the base, and sets the scanner
for a very low beep when reading bar codes. After scanning
this code, the base beep, base and scanner power up beep,
and scanner linking sounds are all silenced. When a bar code
is scanned, the scanner emits a very soft beep.
Nighttime Mode
Low Beeper (Daytime Mode)
Scan the following bar code to set all sounds to on, but at a low
volume. The scanner beep, base beep, base and scanner
power up beep, and scanner linking sounds are all set to low
volume.
Daytime Mode