Abstract
The influence of acoustic absorption laid directly on top of ceiling tiles installed in a two-way suspended grid system was examined to determine the effect that absorption played in ceiling attenuation. Glass fibre acoustic absorption material ranging in thickness from 15 mm to 100 mm was laid, in turn, directly over four different ceiling tile products. An increase in the transmission loss through the plenum sound path was seen when the acoustic absorption was laid over the ceiling tiles. The largest increase seen was with the thickest absorption, with the smallest increase seen with the 15 mm thick glass fibre acoustic absorption. The largest overall gain from a tile with no acoustic absorption behind, accounting for thickness was with the 25 mm thick glass fibre acoustic absorption. It was seen that a relatively poor performing ceiling tile can perform relatively well if a thick absorption product is laid directly on top of the tile in the plenum