G. This Headset-Microphone Kit is designed to fit both the regular and large size Combat Vehicle Crewman\'s Helmet. The electrical characteristics of the kit are compatible with Tactical Radio Systems, such as the VRC-12.

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MIL-DTL-55535A

FIGURE 4. Microphone signal to noise ratio test circuit.

TABLE VI. Noise spectrum.

Sound pressure

Frequency

in dB relative to

in Hz

sound pressure

at 130 Hz

130

300

-5

600

-9

1,000

-13

2,000

-17

3,000

-19

4,000

-21

4.7.3.2 Signal spectrum. By means of the apparatus as set up previously, provision shall also be

made for the production of the following signal spectrum, in table VII at an rms sound pressure of 115 dB

above a reference level of 20 �Pa. The "signal" source shall be the driver unit. The calibrating condenser

microphone shall be positioned 0.25 (�) inch directly in front of the driver unit.