Sound Absorption vs Insulation: What Is the Difference?
People often say "acoustic" when they mean two very different things. One is stopping noise from reaching the next room. The other is stopping echo inside the room. They need different materials and different tests.
Sound insulation: blocking noise between rooms
Sound insulation is about a wall, floor or ceiling and how much sound it stops from passing through. It is measured as STC or Rw. A higher number is better. Think of a thick wall between two bedrooms.
Sound absorption: reducing echo inside a room
Sound absorption is about a surface soaking up sound instead of bouncing it back. It is measured as NRC, a number from 0 to 1. A higher number is better. Think of curtains, carpets and ceiling baffles in a hall. A material can be good at one and poor at the other. A hard, heavy panel can block sound well and still be echoey.
What do the BIOMEBOARD™ tests show?
Insulation. A tested 100 mm partition, with BIOMEBOARD™ on both sides of a 50 mm rockwool core, reached Rw 44 dB (about STC 44). That is a result for the wall, not the board alone. Absorption. A 30 mm board from the same material family was tested at CSIR National Physical Laboratory with a 50 mm air gap behind it. It scored an NRC of 0.22. That is low. For comparison, good sound-absorbing panels usually score much higher. So BIOMEBOARD™ is not an acoustic panel, and we do not sell it as one.
What should you use it for?
- Good fit: partitions between rooms, when built with proper insulation.
- Not the right choice: controlling echo in halls, auditoriums, recording rooms or open offices. Use proper absorbers there.
A simple way to decide
Ask: is the problem noise coming through the wall, or sound bouncing around inside the room? If it is the first, look at insulation (STC or Rw). If it is the second, look at absorption (NRC).
Quick fixes by problem
- Noise from next door: add mass, seal gaps and use insulation in the wall.
- Echo in the room: add soft, porous surfaces such as ceiling tiles, fabric panels, curtains and rugs.
FAQs
What is the difference between sound absorption and insulation?
Absorption reduces echo inside a room. Insulation blocks sound between rooms.
What is NRC?
A score from 0 to 1 for how much sound a surface absorbs.
Does BIOMEBOARD™ have an NRC rating?
Yes, a related 30 mm board scored 0.22 in a lab test, which is low.
Is STC the same as NRC?
No. STC is about blocking. NRC is about absorbing.
What should I use to reduce echo?
Soft, porous materials, such as acoustic ceiling tiles, fabric panels and rugs.
Can one product do both jobs?
In principle yes, but each job needs its own test result. A good score in one says little about the other.
Unsure which problem you have? Describe your room and we will point you the right way.