Normalized sound insulation of a suspended ceiling Dn,f

Definition and scope

Determination of airborne lateral sound insulation of a suspended ceiling.

The measurement shall be performed in a flanking transmission testing facility.

The depth of the air space of the ceiling tested must be between 650 and 760 mm. The separation wall (acoustic barrier between the installation into two rooms) must have a sound insulation 10 dB greater than that of the ceiling that is tested.

Evaluation method according to NF EN 10848-1

Expression of results: Calculation of weighted single index Dn,f,w (C, Ctr) according to NF EN ISO 717/1

Values of Dn,f in third octave bands between 100 and 3150 Hz accounted for, accuracy of 1/10th of a dB.

Vertical displacement of a reference curve by 1 dB jumps until the sum of adverse deviations is the largest while remaining less than or equal to 32 dB.

Dn,f,w is the value given by while the reference curve at 500 Hz

The terms of adaptation to a spectrum (C and Ctr) are calculated using reference spectra. 

Example Dn,f test result