Acoustic Design Considerations for SCIFs in the U.S. & Canada

In the architecture of national security and defense spaces, few environments are as technically demanding as a Sensitive Compartmented Information Facility (SCIF). These specialized rooms are engineered for the secure handling, discussion, and storage of classified or compartmented information. SCIFs are used by government agencies, military organizations, and defense contractors across North America to prevent interception of sensitive data — including through acoustic and vibration-based surveillance.

Whether located within government buildings, embassies, command centers, or leased commercial spaces, SCIFs must block not only physical access but also sound transmission and electronic eavesdropping. Thus, acoustic integrity is a foundational component of SCIF security.

Why Acoustic Design Matters in SCIF Construction

Acoustic design for SCIFs is not about comfort or noise reduction — it’s about ensuring that speech inside is completely undetectable outside the secure boundary. Every detail in construction must support containment, not just attenuation. Achieving that requires a system-level approach that examines airborne noise isolation, structure-borne noise and vibration transmission, acoustic flanking paths and even speech interference techniques.

How SCIFs Differ from Other Acoustically Private Rooms

In conventional offices or meeting rooms, acoustical goals center on a reasonable degree of speech privacy and ambient noise control. In SCIFs the bar is far higher.

In the United States, SCIF design is guided by the Intelligence Community Directive 705 (ICD 705) and the companion Technical Specifications (ICS 705-1 and 705-2).. These documents prescribe construction, shielding, sound attenuation, and verification requirements.

In Canada, secure spaces such as Special Discussion Areas (SDAs) and SCIF facilities are regulated under the Government of Canada Physical Security Program, led by the RCMP Lead Security Agency (LSA). Additional oversight may come from the Communications Security Establishment (CSE) or DND depending on classification. The publicly available GCPSG-017 – Special Discussion Area Construction Guide, published by the RCMP, provides relevant design expectations.

“A ‘SIGINT Secure Area’ (SSA) is a high-security facility for sensitive Signals Intelligence (SIGINT). More specialized than an SDA, it requires top-level government approval. Canada is phasing out ‘SSA,’ adopting ‘SCIF’ to indicate the same security level.”

While the U.S. relies on a unified directive (ICD 705), Canadian standards are distributed across agencies and customized by project classification and authority.

United States: Acoustic Standards under ICD 705

Under ICD 705, SCIFs must satisfy one of the defined Sound Groups, each associated with a minimum Sound Transmission Class (STC) rating:

Sound Group 3: STC 45 or higher — indicates loud speech is unintelligible outside the room.

Sound Group 4: STC 50 or higher — for SCIFs with amplified speech, conferencing, or public address systems.

Importantly, these acoustic requirements apply to the entire acoustic envelope as constructed (walls, doors, ceilings, floors, building services, and penetrations). Because STC ratings are commonly determined in a laboratory under ideal conditions, real-world acoustic performance often falls short of laboratory performance, and field verification according to ASTM E336 – Standard Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings is required to ensure success.

If testing shows performance below the objective, SCIF accreditation or occupancy may be denied or delayed until corrective measures are implemented — highlighting the necessity of early acoustic design coordination of the construction details.

The UFC 4-010-05: SCIF/SAPF Planning, Design, and Construction manual also details minimum construction and acoustic requirements for secure facilities.

Canada: Acoustic Guidelines for SDA and SCIF/SSA Facilities

Canada does not publish a direct equivalent to ICD 705, but acoustic and construction guidance is embedded in the Government of Canada Physical Security Program and related RCMP documentation.

The public standard to reference is GCPSG-017 – Special Discussion Area Construction Guide). This guide outlines required layering, perimeter integrity, and acoustic shielding, although it does not publicly assign explicit STC or NIC values.

Additional RCMP physical security publications and guides (e.g. G1-017, G1-018 relating to doors, hardware, etc.) may also inform design considerations for secure areas in Canada.

SDA vs. SCIF: Understanding the Difference

A Special Discussion Area (SDA) and a SCIF may both host sensitive conversations, but they serve different purposes:

SDA — meant to prevent unauthorized overhearing of classified discussion up to Top Secret levels. It focuses primarily on acoustic privacy and may not meet full physical or surveillance resistance criteria.

SCIF — authorized for Sensitive Compartmented Information (SCI) and demands robust construction against covert entry, audio capture, vibration, and other forms of technical surveillance. A SCIF typically operates under the authority of DND (via the National Special Centre) or CSE in Canada.

Universal Acoustic Design Strategies for SCIFs

Despite some jurisdictional differences, the acoustic design principles for SCIFs are consistent:

1. Sealed acoustic boundary – create the core isolation.
2. Control and eliminate flanking or leakage paths – address secondary vulnerabilities.
3. Supplement isolation with sound masking – add active measures to bolster speech intelligibility and security outside the room.
4. Verify performance with rigorous testing – confirm that all the above measures meet the required security standards.

Here’s how these design principles are typically implemented:

Acoustic Envelope Construction

• Decoupled wall assemblies.
• Isolated floors and ceilings using resilient mounts, neoprene pads, or isolation clips to interrupt structural paths.
• Room-within-a-room construction when maximum isolation is needed; the entire inner shell can be decoupled from the base building.

Doors, Windows, and Penetrations

• STC-rated doorsets (typically STC 50 or higher) with full perimeter gaskets and drop seals.
• Windows, if unavoidable, should use laminated multi-pane isolated glazing in robust frames, continuously sealed to the envelope.
• Utility penetrations (conduit, data ports, etc.) must be adequately detailed to preserve barrier continuity.

Mechanical and Electrical Systems

• Use conventional ductwork attenuation (lined ductwork, duct silencers, acoustic plenums  or transitions at all envelope penetrations.
• Mount mechanical equipment on vibration isolators and, where possible, place units outside the secure boundary with flexible connections.
• Seal and decouple conduits to avoid cavity resonance or indirect transmission.
• Maintain background HVAC noise providing both occupant comfort and beneficial acoustic masking. (See more on Sound Masking below)

Sound Masking and Acoustic Interference Systems

In addition to physical isolation, controlled background noise enhances a SCIF’s acoustic security by masking residual speech transmission through walls or flanking paths. Sound masking prevents Sensitive Compartmented Information (SCI) from being overheard by:

• Reducing speech intelligibility beyond the secure perimeter
• Raising the ambient noise floor to obscure leaks
• Lowering the signal-to-noise ratio of transmitted speech

Techniques Used:

Electronic Sound Masking: Pink or white noise, tuned to speech frequencies (125 Hz–8 kHz), is emitted through concealed speakers. Systems may be constant (uniform) or automatically adjusted (adaptive) using digital signal processors (DSPs).

Active Countermeasures: Noise or vibration is introduced into walls, ducts, or glazing to create controlled “self-noise,” often monitored under under TEMPEST or TSCM programs.

Mechanical Masking: Balanced HVAC noise (NC-35 – NC-40) and broadband duct designs contribute beneficial masking.

Perimeter Masking: Emitters in buffer or interstitial zones neutralize residual transmission at the secure boundary.

Acoustic Verification and Commissioning

• Conduct NIC testing (ASTM E336) for airborne isolation between the SCIF and adjacent areas.
• Perform speech-level (“elevated voice”) tests to assess intelligibility at the boundary.
• Measure ambient noise levels (ASTM E413 or ISO 16283) to ensure background sound supports required confidentiality.

Testing is done under observation by the security authority or approved acoustical consultant. Because remediation can be highly invasive, integrating acoustic design early (during schematic or pre-design phases) is essential.

Conclusion: Acoustic Integrity Is Security Integrity

A SCIF is not just a physically secure room — it is an acoustically armored enclosure, engineered to resist advanced surveillance techniques and preserve classified data integrity. Whether your project is in the U.S. or Canada, understanding the regulatory framework — and involving a qualified acoustical consultant early in design — is critical. Acoustic performance isn’t just a checklist item: it is a core pillar of information and physical security design.