Classification System
[AC] Acoustic Critical
Elements that directly affect measured acoustic performance. Must not be modified, substituted, or omitted without acoustic consultant review and recalculation.
[DEC] Decorative
Elements that affect aesthetics only, or whose acoustic contribution is negligible. Can be customized within the stated constraints.
[AC] Acoustic Critical Elements
| Category | Elements |
|---|---|
| Wall assemblies | All 7 wall types (W1–W7) — material layers, thickness, STC ratings |
| Floor isolation | Sylomer SR28 pads + 25 mm perimeter gap (continuous, unbroken) |
| Ceiling grid height | 275cm AFF — all rooms, no exceptions |
| Acoustic panels | All panels and bass traps — positions, quantities, NRC ratings |
| Door seals | All door seals and thresholds — magnetic compression + drop seal |
| HVAC silencers | All 5 silencer runs — lengths, positions, attenuation values |
| Column isolation | 10mm clearance gaps at COL_W and COL_E — no rigid contact |
| Plenum barriers | Gypsum barriers at every partition, ceiling to structural slab |
| Penetration sealing | All conduit, stagebox, and HVAC penetrations — Rockwool + Tremco |
[DEC] Decorative Elements
| Element | Constraint |
|---|---|
| Panel fabric color and texture | Must be acoustically transparent (light test) and Class A fire rated |
| Ceiling tile color | Must maintain same NRC specification |
| Lighting fixture style | Must be tunable white 2700–3500K, no ceiling penetrations |
| Furniture | No acoustic constraints |
| Floor finish color | No acoustic constraints |
Design Assumptions
| Parameter | Value | Source |
|---|---|---|
| Speed of sound | 343 m/s at 20°C | Standard atmospheric conditions |
| Absorption coefficients | Manufacturer published values | Product data sheets |
| Room geometry | DXF-extracted dimensions | Verified March 28, 2026 by Sara Kalash, Threefold Studio |
| HVAC system | Daikin VRF at specified fan speeds | If IDU replaced, re-verify NC |
| Occupancy | Unoccupied rooms | Person absorption not included — conservative estimate |
Limitations
| Limitation | Impact | Mitigation |
|---|---|---|
| Sabine formula accuracy | ±15% for heavily treated rooms | Eyring correction applied for rooms with α > 0.3 |
| Field STC vs lab STC | Typically 3–7 dB lower in practice | Design values include margin |
| Impact noise | Not addressed in this study | Separate treatment required if needed |
| Low-frequency (<80Hz) | Modal behavior dominates — predictions less reliable | Bass traps target known modal frequencies |
| HVAC performance | Final NC depends on MEP contractor execution | Hold point [HP] at Phase 6 for NC pre-test |
Modification Policy
[AC] Change Control Process: Any modification to an [AC] element requires:
- Written request to acoustic consultant
- Recalculation of affected parameters (RT60, NC, STC)
- Updated documentation reflecting the change
- Re-verification after installation
Unauthorized modifications to [AC] elements void all acoustic performance claims.