What do ceiling acoustic ratings mean?

What is the A to E absorption class?

BS EN ISO 11654 grades absorption from Class A to Class E using the weighted coefficient αw. Class A means αw of 0.90 or more, so at least 90% of the sound that reaches the tile is absorbed. Class B is 0.80–0.85, Class C 0.60–0.75, Class D 0.30–0.55 and Class E 0.15–0.25.

What is Dn,f,w?

It measures room-to-room sound reduction through the ceiling and void, in decibels, tested to BS EN ISO 10848. It matters when partitions stop at the ceiling. Light, highly absorbent tiles often have low attenuation, which surprises people who bought ‘acoustic tiles’ for a meeting room and can still hear next door.

Which one do I need?

If the room is echoey and tiring to talk in, you need absorption, so choose Class A or B. If you can hear the room next door, you need attenuation: denser tiles, a void barrier above the partition, or a partition that goes up to the soffit. Many meeting rooms need both.

Are there rules for schools and hospitals?

Yes. Building Bulletin 93 sets acoustic performance standards for schools, and HTM 08-01 covers healthcare buildings. The project acoustician usually specifies the ceiling to meet them, and we install to that specification.