GB905601A - Sound attenuation - Google Patents

Abstract

905,601. Building units. WOHLBERG, G. Sept. 1, 1958, No. 28007/58. Class 87 (1). [Also in Group XXVII] A sound-attenuating self-supporting discrete structural unit, Fig. 2, has at least one interior chamber 102, imperforate sides 106 and a rectangular sound-attenuating face having formed therein for each chamber a single substantially acoustically unobstructed opening 112 extending substantially across the entire width of the face but not completely across its length, e.g. over from one-quarter to one-half thereof, and forming the only access from the chamber to an exterior sound field. As shown, the opening 102, and perforate or imperforate decks 110 which may have upturned edges 114 and which support glass or stainless steel wool soundabsorbent pads 116, are covered by a permanently secured or screwed-down perforated plate 118, preferably having at least 10% open area. The plate 118 may be dispensed with, the pads 116 being retained by staples, adhesive or wire mesh. The unit, including the members 110, 118, may be of sheet-metal, plywood or " plastic." Externally identical units of the same or differing internal form are used to line room walls. Examples are given of units divided by transverse partitions into two or three chambers of equal or unequal volume. The units may have lugs or flanges to connect them together or to supporting framework, or, if of metal, may be welded together along edge portions. They may form or line one, two opposed or adjacent, three or all four sides of a square or a rectangular section gas passage, or passages in parallel, the units being arranged longitudinally of the passage or passages in a row or side-by-side rows. Where two like units are arranged back-to-back they may be constructed as a single double-faced unit with a central longitudinal partition. The manner of arranging internally different units in a passage to suppress resonance and attain desired attenuation effects is explained in detail, and graphs showing the variation of sound attenuation with frequency are given. In Fig. 36, slides 218 can vary the size of the opening 112, and in Fig. 40 there is an opening 112 at each end of the unit which is divided by a partition 246 into corresponding chambers.