As open-plan offices have become the norm, there is one common complaint we hear from facility managers: "Our office is relatively quiet, but why can't our employees focus?"
The problem is not the volume of noise, but Speech Intelligibility. The quieter the environment, the more clearly you hear phone calls and conversations from adjacent desks, increasing cognitive load and destroying focus. This is called the Speech Privacy problem.
Sound masking is often presented as a silver bullet for this problem. But installing it without proper acoustic diagnosis can make things worse. In this article, we explain the ABM framework (Absorb-Block-Mask), why sound masking alone fails, the right installation order, and how TORNEX ensures correct results through professional consulting.
ABM Framework: Absorb + Block + Mask
The internationally recognized approach for systematically solving office acoustic problems is the ABM (Absorb-Block-Mask) framework. Each element plays a specific role, and missing any one results in an incomplete solution.
ABSORB
BLOCK
MASK
TORNEX is Korea's only Total Acoustic Solution Provider
Offering all three ABM elements — absorption, blocking, and masking — with in-house solutions and professional consulting.
Warning: SM Alone Causes Adverse Effects
There is a misconception that Sound Masking (SM) is a universal solution. However, installing SM without diagnosing the acoustic condition can actually make the problem worse.
"We installed a sound masking system, but the office became even noisier."
— A client who experienced adverse effects from SM installation in a reverberant space and then consulted TORNEX
SM works by injecting uniform background sound to lower the STI (Speech Transmission Index). But this requires two prerequisites:
- The masking sound must be uniformly distributed throughout the space
- The masking sound itself must not be affected by reverberation
In reverberant spaces (RT60 > 0.8s), three problems occur:
1. Energy Build-up
Sound energy from SM speakers repeatedly reflects off walls, ceilings, and floors. Direct + reflected sound overlap causes perceived noise 5-10dB above intended levels (40-48dBA).
2. Spectral Distortion
The SM masking curve (200Hz-5kHz) overlaps with room resonance modes, amplifying certain frequencies and creating an unpleasant "humming" sensation.
3. Spatial Uniformity Loss
SM requires ±2dB uniformity across the space. High reverberation causes uneven distribution — some seats are noisy, others have no effect.
Conclusion: Masking without absorption is not just a waste of money — it creates adverse effects.
The Right Order: Absorption First, Masking Completes
In the ABM framework, A (Absorb) is a prerequisite for M (Mask). This is a technical necessity — without proper absorption, masking cannot function correctly.
| Metric | Absorption Only | SM Only (Reverberant) | Absorption + SM |
|---|---|---|---|
| RT60 | 0.5-0.7s ✓ | 1.0s+ (No change) | 0.5-0.7s ✓ |
| STI | 0.55-0.65 (Moderate) | Unpredictable | 0.35-0.45 ✓ (Privacy) |
| Perceived Noise | Neutral | Increased ✗ | Comfortable ✓ |
| Speech Privacy | Partial | Adverse Possible ✗ | Fully Achieved ✓ |
Absorption creates the acoustic environment where SM can function correctly — reducing reflected sound so SM only needs to mask direct sound at comfortable levels (40-45dBA).
Why Professional Consulting Is Essential
SM is not just about installing speakers. A sequential process of diagnosis → absorption → SM design is essential. TORNEX ensures proper installation through a 5-step workflow:
① On-Site Measurement
RT60, background noise levels, floor plans. Professional measurement as a registered acoustic measurement company.
② 3D Simulation
STI mapping using treble.tech 3D acoustic simulator. Visual comparison of before/after absorption and SM application.
③ Absorption Design
Optimized placement of PET panels, melamine foam, wood wool. Target RT60 ≤ 0.6s.
④ SM Design
Soft dB system zone layout, speaker spacing, masking curve configuration.
⑤ Post-Installation Verification
Verify RT60 changes, STI, and SM uniformity with measured data and fine-tuning.
This process has been repeatedly validated through our consulting experience. "Just install it" leads to adverse effects — only diagnosis-based sequential application produces correct results.
Global Application Examples
Soft dB's sound masking system — 30+ years of acoustic expertise from Canada, deployed in thousands of facilities worldwide.
| Space Type | Key Challenge | ABM Application | Expected Effect |
|---|---|---|---|
| Open-Plan Office | Focus loss from speech noise | Ceiling PET absorption + Carpet + SM | Lower STI → Privacy |
| Meeting Room Adjacent | Meeting content leakage | Wall absorption + Partition + Directional SM | Confidential protection |
| Healthcare Facility | Patient privacy | Clinic absorption + SM | HIPAA-level Privacy |
| Financial Institution | Client confidentiality | Counter absorption + Directional SM | Transaction protection |
Domestic Reference: Hyundai E&C President/VP Offices
TORNEX has completed the installation of a Soft dB sound masking system at Hyundai E&C's top executive offices — the first such application in a major Korean corporation. Executive meeting confidentiality and Speech Privacy have been secured.
Request Free Acoustic Diagnosis
Sound masking is not a universal solution. The right approach is to first diagnose the acoustic condition, establish the foundation with absorption, then complete it with masking. This is why TORNEX provides professional consulting alongside our products.
Request Free Acoustic Diagnosis
Learn More:
Related News: TORNEX Builds Korea's Only ABM Integrated Acoustic Solution Through Soft dB Partnership
Interested in the products discussed in this article?
View Product → Sound Masking