Parafon Decibel is a series of suspended ceiling products with sound insulating and sound absorbing properties whose primary area of application is sound reduction between rooms in buildings where the intermediate walls do not extend all the way up to the floor. Parafon Decibel Mass is well tested and documented in the field; a Parafon classic with plaster as a sound insulating component and non-combustible stone wool for sound absorption. If for whatever reason you want to avoid insulating with Decibel Barrier in the plenum, the solution is to use Decibel Mass in combination with the Parafon Bass sound absorber which is placed above the suspended ceiling, which provides sound insulation via the suspended ceiling of up to D_n,f,w 48 dB.