PTB – Physikalisch-Technische Bundesanstalt

Perforated drywall, 0.5% perforation ratio (Meyer, Kirchenakustik)

Perforated gypsum board, 12/20 mm hole diameter

Perforated gypsum board with 6% perforation ratio

Perforated gypsum board, 19.6% open area, 15 mm hole diameter, 100 mm cavity

Plasterboard 9.5 mm with 6 mm holes in square pattern with approx. 11% perforation. 100 mm from wall with 25 mm mineral wool at front of cavity

Perforated gypsum cassette with mineral fiber inlay

Perforated gypsum cassette with mineral fiber inlay and aluminum foil

Wood panels, 6% perforation ratio / 5 cm air cavity

Perforated metal cassette with mineral fiber backing, spacing 180 mm

Perforated metal cassette with mineral fiber backing, spacing 350 mm

Perforated metal cassette ceiling with 20 mm Sillan acoustic panels

Perforated metal panel ceiling, 20 mm Sillan acoustic panels, 350 mm cavity

Perforated metal plate with non-woven facing

Walls, panel with slot 16 mm, on 25 mm studs with mineral wool

3.5-4 mm boards (asbestos, plywood or hard fiberboard), 13% perforation

Perforated steel panel backed by 4 inch layer of 2 pcf OCF Type R-23 Fiberglas

Perforated steel panel backed by 2 inch layer of 2 pcf OCF Type RA-23 Fiberglass

Transite, 3/16 inch perforated cement-asbestos board, 11% open area

Transite, 3/16 inch perforated cement-asbestos board, 11% open area

55 mm perforated bricks on edge, 78 holes per brick, 11% perforation

55 mm perforated bricks on edge, 78 holes per brick, 11% perforation, no cavity

Perforated glazed stoneware molded element

Perforated brick 8x30x15 cm with 6 holes, F/A = 60% + whitewash

Perforated brick 12x25x25, 60% open area, whitewashed

Perforated brick 8x12x24 cm with 4 holes, F/A = 60% + whitewash

perforated brick 12x25x25 cm with 10 holes F/A = 60% + whitewash (series 2)

Perforated steel panel backed by 4 inch layer of 3 1/2 pcf USG Thermafiber in Mylar

Perforated sheet corrugated to key pattern (CoopSe)

grooved wood covering

Chairs, upholstered concert chairs, empty

α per m² audience area

invented padded arm-chair

α per m² audience area

Ceilings, 16 mm pressed mineral fiber board (fissured) 20 mm from ceiling

Slotted gypsum board cassette (DNA 1968, b2.2-1a)

Slotted gypsum board cassette, 625 x 625 mm, 9.5 mm thick (DNA 1968, b2.2-1b)

Slotted gypsum board tile, 625 x 625 mm, 9.5 mm thick (DNA 1968, b2.2-3)

Sprayed Limpet asbestos, 1 inch, 1 coat, unpainted on solid backing

Sprayed Limpet asbestos, 3/4 inch, 1 coat, unpainted on solid backing

Sprayed Limpet asbestos, 3/4 inch, 1 coat, unpainted on metal lath

Painted wall in CLS (C)

Seating, unoccupied, moderately upholstered, 0.90 m x 0.55 m

α per m² audience area

sheet corrugated to key pattern thickness = 1 mm

Plaster, gypsum, or lime, smooth finish on lath

Plaster, gypsum, or lime, smooth finish on tile or brick

Plaster, gypsum or lime, rough finish on lath

Plaster, gypsum, or lime, rough finish on lath

Plaster ceiling, 60 mm with lighting & ventilation

Plaster ceiling, 30 mm with lighting & ventilation

Painted plaster surface