Audio Engineering

Room Acoustics 853

would short-circuit the isolation and negate the whole effect. With such constructions,
particular care has to be taken with the connection of the various services into the studio.
Again attention to detail is of tantamount importance if optimum performance is to be
achieved. Note that the sealing of any small gaps or cracks is extremely important, as
shown by the plastered and unplastered walls in Table 29.4.

Table 29.4 : Summary of Some Typical Building Materials

Materials SRI (dB)

Walls

Lightweight block work (not plastered) 35

(plastered) 40

200-mm lightweight concrete slabs 40

100-mm solid brickwork (unplastered) 42

(plastered 12 mm) 45

110-mm dense concrete (sealed) 45

150-mm dense concrete (sealed) 47

230-mm solid brick (unplastered) 48

(plastered) 49

200-mm dense concrete (blocks well sealed/plastered) 50

250-mm cavity brick wall (i.e., 2 110) 50

340-mm brickwork (plastered both sides 12 mm) 53

450-mm brick/stone plastered 55

112-mm brick  50-mm partition of one layer plasterboard and softboard per side 56

225 brick—50 mm cavity—225 brick 65

325 brick—230 mm cavity—225 brick (fl oated) 75

12-mm plasterboard on each side of 50-mm stud frame 33

12-mm plasterboard on each side of 50-mm stud frame with quilt in cavity 36

T w o 12-mm plasterboard on 50-mm studs with quilt in cavity 41

As above with 75-mm cavity 45

Three layers of 12-mm plasterboard on separate timber frame with 225-mm air gap

with quilt

49

(Continued)