How to write an absorber line so it can be priced.

01

Reverberation is the complaint, even when nobody names it

When someone says a room is ‘loud’ although nobody is shouting, the problem is usually the tail of the sound, not the source. RT60 is the time sound takes to fall 60 decibels after the source stops. In a glazed meeting room it can pass a second and a half, so two consonants land on top of each other.

Sabine’s planning equation: RT60 ≈ 0.161 × volume ÷ the sum of (area × absorption coefficient). The calculator applies it in the open, with mid-frequency coefficients, not a tested curve for every band. That is why it is a compass, not a stamp.

02

The order of the line in the schedule

First the ceiling: an area, not a decorative object. Second a wall at the speaking position if glass remains. Third baffles if the soffit stays open for services. Fourth partitions and desk screens for short distance. metal enters when the tail below 250 Hz stays long after the textile area is complete.

03

What travels with the tender

The full system name (board S40, not ‘a Lindner absorber’), thickness, position, square metres, the absorption class of that system, and its own fire requirement. One family’s certificate is not pasted onto another. More than 150 tested measurements exist at the factory for this purpose.

For health on board S24: mineral-fibre free, Oeko-Tex® Standard 100, Indoor Air Comfort GOLD. Repeat the sentence only for the system whose sheet actually carries it.

04

A note for specifiers in the region

Full-height glass, polished stone, a low majlis and a hotel atrium are patterns that repeat. This site does not invent client names that were never published. It offers a way to specify: calculate the volume; do not guess a panel count that ‘looks like enough’ in a rendering. The notes page goes further on majlis, atriums and schools.