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1947-48 Theatre Catalog, 6th Edition, Page 173 (161)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 173
Page 173


1947-48 Theatre Catalog, 6th Edition, Page 173

The data (Table l) on the acoustical absorption of the tile and board (1 inch thick) are derived from tests conducted by the official Acoustical Materials Association Laboratory (Riverbank Laboratories). The material was mounted on supports (24 inches on centers) 10% inches from the boundary surface of the sound chamber.

TABLE 1 -Absorption coeflicients of Fiberglas tile and 1-inch board.



Frequency Absorption



(Cycles) ('oefh'cient 128 . . . . . , . . , . , . . . . . . . . . . . 67

256 . , . . . . . . . . . . . . . . . . . 67

512 , . , , . . . . , . . . . , . . . . . . . . 82

1024 . . . , . . . . . . . , . . . , . . . . . . .89

2048 . . . . . . . . . . . . . . . . . . . . . . 91

4000 . . . . , . . . . . . . . . . . . . . . . , 98



The noise reduction coefiicientethe average of the coefficients at frequencies of 256, 512, 1024, and 2048 cycles, given toithe nearest 5 percent-was found to be 0.80.

ACOUSTl-DECORATION

Decorative fabrics woven of Fiberglas yarns may be used primarily for decorative effect, as in draperies, stage curtains and backdrops; or they may be used as wall or ceiling coverings, backed by non-combustible Fiberglas sound-absorbing materials, for both decorative and acoustical effect. The sound-absorbing materials consist of line glass fibers lightly bonded with a resin. They are ordinarin installed in a one-inch thickness.

Acoustical values are given in Table 2 for the combination of a Fiberglas sound-absorbing material, and a decorative fabric woven of glass yarns weighing two and three-quarters ounces a square yard, 50 percent gathered (cloth area twice actual area of hung drapery), and spaced 10 inches from the wall.

TABLE 2eSound absorption coefficients at 512 cycles (value used in making acoustical analysis of an auditorium) and noise reduction coefficients (value used for sound-quieting in such places as restaurants, cafeteria, and so forth) of unbacked and backed Fiberglas.



Sound Absorption Noise (iericient Reduction (512 cycles) (Ioeflicient

Fabric, backed with l-inch-thick Fiberglas (Code H33,

Type A) . . . . . . . ..74 .70 Fabric, alone, Without backing . . . . ..45 .40



Similar values can be assumed for the fabric used as draperies on stages, or hung in open doorways.

INSTALLATION METHODS

A variety of methods can be employed in installing the fabrics and sound-absorbing material. The latter can be nailed to the walls or ceilings or held in place by furring strips; or it can be laid on Fiberglass cord stretched from wall to wall 10 to 12 inches below the ceiling. The third method (illustrated) is particularly applicable to ceilings with through beams and exposed pipes and conduits.

1947-48 THEATRE CATALOG



INSTALLATION oi Piberqlas materials is a relatively simple procedure. Above is seen workmen rolling out Fiberglas rooting mat in a standard three-ply construction. In the center picture is seen the installation of Fiberglas acoustical board which is laid between rows of recessed fluorescent light trotters. Fiberglas materials are available tor acoustical as well as tor thermal Insulation.



THERMAL INSULATION is used in ceilings (below). walls, floors, and roots. It cuts tuel costs, makes possible use of smaller and less expensive heating units, and provides closer temperature control. Many uses of Fiberglu-s matriuls in theatres are essentially Similar to uses a! the materials in other types of buildings and the characteristics can well be applied here in all cases.
1947-48 Theatre Catalog, 6th Edition, Page 173