IC Tech Spec for ICD/ICS 705

Sound Transmission Mitigations

1. Construction of walls as described in Chapter 3 (Wall types A, B and C) or with brick, concrete, or other substantive material and acoustically treating penetrations, walls and doors should provide the necessary acoustic protection for Sound group 3.
2. When Sound Group 3 or 4 cannot be met with normal construction, supplemental mitigations to protect classified discussions from being overheard by unauthorized persons may include but not be limited to the following:
1. Structural enhancements such as the use of high-density building materials (i.e., sound deadening materials) can be used to increase the resistance of the perimeter to vibration at audio frequencies.
2. Facility design can include a perimeter location or stand-off distance which prevents non-SCI-indoctrinated person(s) traversing beyond the point where SCI discussions become susceptible to interception. For example, use of a perimeter fence or protective zone between the SCIF perimeter walls and the closest "listening place" is permitted as an alternative to other sound protection measures.
3. Sound masking devices, in conjunction with an amplifier and speakers or transducers, can be used to generate and distribute vibrations or noise; noise sources may be noise generators, tapes, discs, or digital audio players.
4. Speakers/transducers must produce sound at a higher level than the voice conversations within the SCIF.
5. Speakers/transducers shall be placed close to, or mounted on, any paths that would allow audio to leave the area, including doors, windows, common perimeter walls, vents/ducts, and any other means by which voice can leave the SCIF.
6. Wires and transducers shall, to the greatest extent possible, be located within the perimeter of the SCIF.
7. The sound masking system shall be subject to inspection during TSCM evaluations.
8. If the AO determines risk to be low, a speaker may be installed outside the SCIF door if the following conditions are met:
• The cable exiting the SCIF shall be encased within rigid conduit.
• The sound masking system shall be subject to review during TSCM evaluations.
9. For common walls, the speakers/transducers shall be placed so the sound optimizes the acoustical protection.
10. For doors and windows, the speakers/transducers shall be placed close to the aperture of the window or door and the sound projected in a direction facing away from conversations.
11. Once the speakers or transducers are optimally placed, the system volume shall be set and fixed. The volume level for each speaker shall be determined by listening to conversations outside the SCIF or area to be protected, and the speaker volume adjusted until conversations are unintelligible from outside the SCIF.
12. Sound-source generators shall be permanently installed and not contain an AM/FM receiver and shall be located within the SCIF.
13. Any sound-source generator within the SCIF that is equipped with a capability to record ambient sound shall have that capability disabled.
14. Examples of government-owned or government-sponsored sound-source generators are given below:
• Audio amplifier with a standalone computer (no network connection).
• Audio amplifier with a cassette tape player, compact disc (CD) player, or digital audio player, or with a digital audio tape (DAT) playback unit.
• Integrated amplifier and playback unit incorporating any of the above music sources.
• A noise generator or shift noise source generator using either white or pink noise.