Understanding STC Ratings and Their Role in Soundproofing Walls
What is STC and Why Does It Matter?
STC (Sound Transmission Class) is the standard measure of how well a wall, door, window, or partition blocks airborne sound. It indicates the decibel (dB) reduction of noise as it passes through a structure.
Higher STC = better sound isolation and improved privacy.
Applications of Soundproofing
Apartments & Homes: Blocking neighbor noise or traffic sounds
Offices & Boardrooms: Ensuring speech confidentiality
Hotels & Hospitals: Creating quiet, restful environments
Studios & Theatres: Preventing sound leakage between rooms
How STC Ratings Are Measured
Measurement Method: STC is determined by ASTM E90 testing in a controlled lab. It measures how much sound (in dB) is reduced between 125 Hz and 4000 Hz (typical speech and noise range).
Example: A wall with STC 50 blocks most speech and TV noise.
Comparison
STC 25: Normal conversation easily heard
STC 35: Loud speech still audible
STC 50+: Excellent privacy; loud sounds are barely perceptible
Recommended STC Levels for Different Spaces
Apartments/Shared Walls: STC 50+
Bedrooms (Urban Homes): STC 45–50
Corporate Boardrooms: STC 55+ (speech privacy critical)
Hotels/Hospitals: STC 50+
Studios/Theatres: STC 55–60+ (high isolation)
How to Increase Wall STC
Walls need mass, decoupling, and damping layers to achieve higher STC ratings.
1. SoundBlanket® MLV (Mass Loaded Vinyl)
STC Range: 27–40 (2–10 mm)
Application: Installed behind drywall to add dense, flexible mass
Size: 32 x 4 ft rolls for seamless coverage
Result: Significant airborne sound reduction
2. BassBloc® (Low-Frequency Damping)
Role: Targets low-end bass and vibration not covered in STC ratings but crucial for real-world comfort
NRC: 0.85 (20 mm) | 0.95 (40 mm)
3. Double Stud or Decoupled Walls
Independent wall framing reduces vibration transfer, boosting STC by 8–12 points
4. Acoustic Finishes
Adding fabrics, felt panels (NRC 0.90), or foam reduces internal reflections, complementing high-STC isolation
STC in Real-World Wall Systems
Single Layer Wall (Brick/Cement): STC ~35
Common in apartments; insufficient for urban or premium projects
MLV + BassBloc® + Drywall: STC 50+
Meets hotel, office, and apartment privacy standards
MLV + BassBloc® + Double Stud Wall: STC 55+
Ideal for studios, theatres, or confidential boardrooms
Case Study: Executive Office Sound Isolation (Gurgaon)
Problem:
Speech from adjacent office audible in meetings.
Result:
Composite wall achieved STC 54, delivering complete speech privacy.
Professional Fix:
Installed SoundBlanket® MLV 4 mm (STC 32) behind gypsum partitions.
Added BassBloc® 20 mm for vibration damping.
FAQs
A: No. STC measures airborne sound isolation (speech, TV). For impact noise (footsteps, vibrations), add BassBloc® or floating floors.
A: Yes. STC measures sound blocking, while NRC measures sound absorption (echo control).
A: Yes. MLV, BassBloc®, and additional drywall layers can retrofit existing walls.
Conclusion: Build Walls That Deliver True Silence
STC ratings define soundproofing performance. For homes, offices, or studios, combining SoundBlanket® MLV (STC-rated), BassBloc® (low-frequency damping), and acoustic finishes ensures ASTM-compliant sound isolation for any premium project.
Contact MMT Acoustix today for STC-tested wall systems, datasheets, and acoustic consultancy for residential, corporate, and institutional projects
STC (Sound Transmission Class) is the standard measure of how well a wall, door, window, or partition blocks airborne sound. It indicates the decibel (dB) reduction of noise as it passes through a structure.
Higher STC = better sound isolation and improved privacy.
Applications of Soundproofing
Apartments & Homes: Blocking neighbor noise or traffic sounds
Offices & Boardrooms: Ensuring speech confidentiality
Hotels & Hospitals: Creating quiet, restful environments
Studios & Theatres: Preventing sound leakage between rooms
How STC Ratings Are Measured
Measurement Method: STC is determined by ASTM E90 testing in a controlled lab. It measures how much sound (in dB) is reduced between 125 Hz and 4000 Hz (typical speech and noise range).
Example: A wall with STC 50 blocks most speech and TV noise.
Comparison
STC 25: Normal conversation easily heard
STC 35: Loud speech still audible
STC 50+: Excellent privacy; loud sounds are barely perceptible
Recommended STC Levels for Different Spaces
Apartments/Shared Walls: STC 50+
Bedrooms (Urban Homes): STC 45–50
Corporate Boardrooms: STC 55+ (speech privacy critical)
Hotels/Hospitals: STC 50+
Studios/Theatres: STC 55–60+ (high isolation)
How to Increase Wall STC
Walls need mass, decoupling, and damping layers to achieve higher STC ratings.
1. SoundBlanket® MLV (Mass Loaded Vinyl)
STC Range: 27–40 (2–10 mm)
Application: Installed behind drywall to add dense, flexible mass
Size: 32 x 4 ft rolls for seamless coverage
Result: Significant airborne sound reduction
2. BassBloc® (Low-Frequency Damping)
Role: Targets low-end bass and vibration not covered in STC ratings but crucial for real-world comfort
NRC: 0.85 (20 mm) | 0.95 (40 mm)
3. Double Stud or Decoupled Walls
Independent wall framing reduces vibration transfer, boosting STC by 8–12 points
4. Acoustic Finishes
Adding fabrics, felt panels (NRC 0.90), or foam reduces internal reflections, complementing high-STC isolation
STC in Real-World Wall Systems
Single Layer Wall (Brick/Cement): STC ~35
Common in apartments; insufficient for urban or premium projects
MLV + BassBloc® + Drywall: STC 50+
Meets hotel, office, and apartment privacy standards
MLV + BassBloc® + Double Stud Wall: STC 55+
Ideal for studios, theatres, or confidential boardrooms
Case Study: Executive Office Sound Isolation (Gurgaon)
Problem:
Speech from adjacent office audible in meetings.
Result:
Composite wall achieved STC 54, delivering complete speech privacy.
Professional Fix:
Installed SoundBlanket® MLV 4 mm (STC 32) behind gypsum partitions.
Added BassBloc® 20 mm for vibration damping.
FAQs
A: No. STC measures airborne sound isolation (speech, TV). For impact noise (footsteps, vibrations), add BassBloc® or floating floors.
A: Yes. STC measures sound blocking, while NRC measures sound absorption (echo control).
A: Yes. MLV, BassBloc®, and additional drywall layers can retrofit existing walls.
Conclusion: Build Walls That Deliver True Silence
STC ratings define soundproofing performance. For homes, offices, or studios, combining SoundBlanket® MLV (STC-rated), BassBloc® (low-frequency damping), and acoustic finishes ensures ASTM-compliant sound isolation for any premium project.
Contact MMT Acoustix today for STC-tested wall systems, datasheets, and acoustic consultancy for residential, corporate, and institutional projects