Acoustics — Measurements of sound insulation in buildings and of building elements Part 9: Laboratory measurement of room-to-room airborne sound insulation of a suspended ceiling with a plenum above it
This part of ISO 140 specifies a laboratory method of measuring the airborne sound insulation of a suspended ceiling with a plenum of defined height mounted above an acoustical barrier which separates two rooms of a specified test facility.
This method utilizes a laboratory space so arranged that it simulates a pair of horizontally adjacent, typical offices or rooms sharing a common suspended ceiling system, plenum space and a dividing wall. The dividing wall extends to the underside of the ceiling system which at the junction is either continuous or discontinuous.
The quantity being measured is the airborne sound insulation between two rooms of a specified test facility when the sound transmitted by paths other than the suspended ceiling and common plenum space is negligible. This quantity is called the suspended ceiling normalized level difference.
The method may be extended to include the study of composite ceiling systems comprising the ceiling material and other components such as luminaires and ventilating systems.
The method may also be extended to the study of the additional sound insulation that may be achieved by auxiliary systems, such as material used either as plenum barriers or as backing for all of, or part of, the ceiling.