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
토넥스는 국내 유일의 종합 음향 솔루션 파트너입니다
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. 공간 균일성 파괴
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
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Related News: TORNEX Builds Korea's Only ABM Integrated Acoustic Solution Through Soft dB Partnership
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View Product → Sound Masking자주 묻는 질문(FAQ) — 사운드마스킹과 음향 설계
Q. 흡음 처리 없이 사운드마스킹만 설치하면 왜 역효과가 날 수 있나요?
A. 사운드마스킹은 배경 소음 수준을 높여 대화의 명료도를 낮추는 방식입니다. 그런데 반사면이 많은 잔향이 긴 공간에서는 마스킹 소리 자체가 잔향하며 왜곡되어 소음 문제를 해결하기는커녕 증폭시킵니다. 올바른 순서는: 먼저 흡음으로 잔향을 줄인 후 마스킹을 적용하는 것입니다. 흡음은 선택 사항이 아니라 사운드마스킹의 선결 조건입니다.
Q. 사무실 음향 설계의 ABM 프레임워크란 무엇인가요?
A. ABM은 흡음(Absorb: 흡음 패널로 에코 감소), 차음(Block: 물리적 파티션·장벽 추가), 마스킹(Mask: 사운드마스킹 시스템 적용)의 순서를 의미합니다. 이 순서가 핵심입니다 — 잔향이 큰 공간에서는 마스킹이 효과를 발휘하지 못합니다. 제대로 된 음향 진단이 설치 전에 어떤 요소가 어떤 우선순위로 필요한지를 결정합니다. 토넥스는 ABM 컨설팅을 음향 설계 서비스의 일환으로 제공합니다.
Q. 우리 사무실에 사운드마스킹이 필요한지 어떻게 알 수 있나요?
A. 다음 경우에 사운드마스킹이 유효합니다: ①오픈 사무실에서 대화 프라이버시가 중요한 경우(법적 또는 기밀 대화), ②배경소음이 지속적으로 40 dBA 미만인 경우(너무 조용해 모든 대화가 들림), ③흡음·차음 처리 후에도 잔여 명료도 문제가 지속되는 경우. 마스킹 필요 여부는 배경소음 수준, RT60, STI 측정이라는 객관적 방법으로 판단해야 합니다.
Q. Speech Privacy(대화 프라이버시)란 무엇이고 어떻게 측정하나요?
A. Speech Privacy는 의도하지 않은 청취자가 대화 내용을 이해할 수 없는 정도를 의미합니다. Privacy Index(PI) 또는 STI(Speech Transmission Index)로 정량화됩니다. 수신 위치에서 PI 95% 이상 또는 STI 0.20 미만이면 양호한 대화 프라이버시를 의미합니다. 오픈플랜 사무실 음향 성능 측정 기준은 ASTM E1130 및 ISO 3382-3을 따릅니다.
Q. 사운드마스킹이 흡음 패널을 대체할 수 있나요?
A. 아닙니다. 사운드마스킹과 흡음 패널은 근본적으로 다른 문제를 해결합니다. 마스킹은 배경소음을 높여 도청자에게 대화가 들리지 않게 하고, 흡음 패널은 에코·잔향을 줄여 청자에게 대화가 명확하게 들리게 합니다. 이 두 가지는 상호 보완 관계이며 대체 관계가 아닙니다. 대부분의 사무실에서는 흡음 처리가 먼저 필요하며, 마스킹은 대화 프라이버시를 위한 보조 수단으로 추가됩니다.