Specifications

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MII/STD-1472E
5.3.6 Controls for audio warning devices.
5.3.6.1 Automatic or manual shut-off. When an audio signal is designed to persist as long as it
contributes useful information, a shut-off switch, controllable by the operator, the sensing mechanism,
or both, shall be provided, depending on the operational situation and safety factors.
5.3.6.2 Automatic rtwt. Whether an audio warning signal is designed to be terminated
automatically, manually, or both, an automatic reset function shall be provided. The automatic reset
function shall be controlled by the sensing mdianism which shall recycle the signal system to a
specified condition as a function of time or the state of the signaling system so that the warning device
can sound again if the condition repeats.
5.3.6.3 Redundant Visual Warning. AUnon-verbal aural annunciations shall be accompanied
by a visual annunciation which defines the condition. In a cockpit, this maybe an illuminated display.
In the case of a warning horn on a backing vehicle, the vehicle’s backward motion is adequate
redundancy.
5.3.6.4 Vohum?contd
5.3.6.4.1 Automatic or manual. The volume (loudness) of an audio warning signal shall be
designed to be controlled by the operator, the sensing mechanism, or both, depending on the
operational situation and personnel safety factors. Control movements shall be restricted to prevent
reducing the volume to an inaudible level.
5.3.6.4.2 Gan@rM
to mode switches. Volume cmtrols may be ganged to mode switches to
provide hma~d~tiim p-wtib~-ti= wy~tim~~~
volume at
other times. Ganging shall not be used if intense noise may occur during an emergency in a
mission phase when the volume would be decreased below an audible level.
5.3.6.4.3 Caution si
d controls. Audio caution signals shall be provided with manual reset
and volume controls.
5.3.6.5 Duration. Audio warning signal duration shall beat kast 0.5 second, and may continue
until the approprhte response is made. Completion of a wrmctive tction by the operator or by other
means shall litttomtltidy W’min@
the signal.
5.3.6.6 Duration lhitations. Signals that persist or incxease progressively in level shall not be
used for emergency situations if manual shut-off may interfere with the corrective action rapired.
5.3.7
Speech transmission euuiment.
5.3.7.1 Fmctuency. Microphones and associated system-input devices shall respond optimdiy
to that part of the spech spectrum most essential to intelligibility (i.e., 200 to 6,100 Hz). Where
system engineering necessitates speech-tmnsrnission bandwidths
nanuwerthan 200t06,100Hz, the
minimum acceptabk hquertcy range shall be 250 to 4,000 Hz.
5.3,7.2
Dynamic range.
The dynamic range of a microphone used with a selected ampiifier
shall be wide enough to admit variations in signal input of at least 50 dB.
5 ‘4 7 ~ ~ojsc canceling mjc
. .
rophmm In very loud, low frequency noise environments ( i00
(IB overall),
noise canceling microphones shall he u,sed and shall be capable of achieving an
iIIIIII (}J t’11)(>111l~fnot k’s~[hiin 10 d13 pc:Ik ~perch In root mean-square-noiw rntio as cnmp:]rd Ikrith
I)(NI-
noi.w-wncelinp nticrophunes of equivalcn[ transmission characteristics.