If you’ve ever researched acoustics, you’ve probably seen the terms NRC and STC.
Most explanations online are filled with formulas, graphs, and complicated physics.

This guide breaks them down in a simple, everyday way, so you know exactly:

• what NRC measures
• what STC measures
• which one you need
• how they affect comfort, noise, and clarity

What Is NRC? (Noise Reduction Coefficient)

NRC = how well a material absorbs sound inside a room.

It tells you how well something reduces:

• echo
• reverberation
• reflections
• noise bouncing around

What NRC affects

• speech clarity
• comfort
• meeting room quality
• echo reduction
• home living experience

Common NRC materials

• fabric acoustic panels
• acoustic ceiling tiles
• foam panels
• curtains
• carpets & rugs

Simple rule:
✔ High NRC = less echo
✔ Low NRC = more echo

Read more on Echo vs Reverberation

What Is STC? (Sound Transmission Class)

STC = how well a wall, door, or material blocks sound from travelling through it.

STC is for soundproofing, not echo control.

What STC affects

• privacy between rooms
• preventing noise from upstairs
• reducing neighbour noise
• blocking traffic or machinery noise
• stopping office room leakage

Common STC materials

• walls with insulation
• MLV (Mass Loaded Vinyl)
• treated plasterboard walls
• sealed solid-core doors
• soundproof partitions

Simple rule:
✔ High STC = better sound blocking
✔ Low STC = noise leakage

NRC vs STC — What’s the Difference?

NRC	STC
Measures absorption	Measures sound blocking
Reduces echo	Reduces noise travel
Used inside the room	Used between rooms
Good for clarity	Good for privacy
Panels, fabrics, ceilings	Walls, floors, doors

Most spaces need BOTH — but for different reasons.

When Do You Need NRC?

Use NRC when the room feels:

• echoey
• noisy
• unclear
• boomy
• uncomfortable

NRC is ideal for:

• meeting rooms
• home living rooms
• offices
• classrooms
• restaurants
• worship spaces

Read more on What is Acoustics? and Why Acoustics Matters.

When Do You Need STC?

Use STC when:

• sound leaks between rooms
• privacy is needed
• noise travels through walls or doors
• neighbours complain
• traffic noise enters the room

STC is essential for:

• bedrooms
• home studios
• offices
• consultation rooms
• schools
• medical rooms

You can find out Services here.

Should You Choose NRC or STC?

✔ If the problem is echo inside the room → You need NRC

Use:

• acoustic panels
• ceiling baffles
• soft furnishings

✔ If the problem is noise travelling through walls/doors → You need STC

Use:

• MLV
• door seal kits
• upgraded partitions
• insulation systems

✔ Many spaces need both NRC and STC

Especially:

• offices
• meeting rooms
• schools
• halls
• homes with thin walls

Read more on:
(Echo vs Reverb)
(Noise Between Rooms)
(Soundproof a Door)

Check out our products/services:
MLV Product Page
Door Seal Kit Page
Service Page

If you need any assistance, please feel free to Contact Us