US1992509A

US1992509A - Sound absorbing construction

Info

Publication number: US1992509A
Application number: US562634A
Authority: US
Inventors: Slidell Kemper
Original assignee: CF Burgess Laboratories Inc
Current assignee: CF Burgess Laboratories Inc
Priority date: 1931-09-14
Filing date: 1931-09-14
Publication date: 1935-02-26
Anticipated expiration: 1952-02-26

Description

Feb. 26, 1935. K. SLIDELL' 1,992,509

SOUND ABSORBING CONSTRUCTION Filed Sept. 14, 1931 4 Sheets-Sheet 1 Feb. 26, 1935. K. SLIDELL SOUND ABSORBING CONSTRUCTION Filed Sept. 14, 1951 4 Sheets-Sheet 2 Feb. 26, 1935. 5

scum) ABSORBING CONSTRUCTION 1931 4 Sheets-Sheet 3 Filed Sept l4 Feb. 26, 1935. K. SLIDELL SOUND ABSORBING CONSTRUCTION Filed Sept. 14, 1931 4 Sheets-Sheet 4 ooooooo0 o0o0 L/L 'I' was: @gw

Patented Feb. 26, 1935 un ts!) STATES 1.992.509 SOUND ans'oaamo ooNsraUc'rroN Kemper Slidell, Madison, Wis.. aasignor' to C. F. Burgess Laboratories, Inc., Madison, Wis., a corporation of Delaware Application September 14, 1931, Serial No. 562,834

25 Claim.

This invention relates to improvements in sound absorbing constructions embodying the use of a rigid foraminous facing membrane for sound absorbing materials adapted to be applied to walls, ceilings and the like. The invention ap-' plies more particularly to improvements in constructions wherein the sound absorbing material,

in the form of units, is concealed by self-sustaining foraminous facing membranes such as are described in Norris Patent 1,726,500 issued August 27, 1929.

In the usual construction of this type, the sound absorbing material and the facing membranes, in the form of pans, are brought to the building r separately and are there assembled by the workmen. The sound absorbing units are usually of flexible character, such as soft hair felt pads, and are smaller in area than the pans, to facilitate assembly by the workmen and the units are usu- 20 ally supported by.the pan and rest directly in contact with the reverse or inner side of said pan,

the outer surface of the latter being exposed to a the sound waves.

It has been found that where the sound absorbing unit is smaller in area than the pan there is increased circulation of air (called fbreathing) at the portions of the pan where there is no absorbing material with the result that at those portions, the pan becomes soiled more quickly by de- 3Q posits of dust and the exposed surface presents an objectionable unevenness of color. The same is true where the bottom surface of the absorbing unit is rough and the contact between the abutting surfaces of the pan and the unit is not uniform. Under these conditions, the pan becomes soiled more quickly at those parts where the unit is not in contact therewith. It has also been found that where the sound absorbing material rests directly against the innerpan surface, wa-

ter or cleaning solutionsused upon the exposed 1 surface of said pan soak into the sound absorbing material, impairing its sound absorbing properties to some extent and causing discoloration, if there is any leaching action upon the absorbent. Furthermore, when the surface is painted, with insuiflcient care, paint may soak into the sound absorbing material and tends to partially clog the openings in the pan. In addition, uneven contact between the pan and the absorbing material has the further effect of varying the light reflecting properties of the eirposed surface with the resulting appearance of further unevenness of color.

It is the object of my invention to provide an improved sound absorbing construction in which the above mentioned objections are avoided by an arrangement in which the area of the sound absorbing unit is practically coextensive with that of the facing membrane and in which the adja- 1 cent surfaces of the absorbing unit and the facing membrane are spaced apart.

Another object of the invention is to provide a construction which may be assembled and substantially permanently united at the place of manufacture, to form complete sound absorbing tiles with the resulting advantages of lower production costs, greater exactness and uniformity of product and greater simplicity of installation operations.

Briefly, the foregoing objects are accomplished by constructing the sound absorbing material in the form of units and attaching each unit at its edges to the adjacent sides of the pan-like facing member and maintaining the adjacent surfaces of the unit and the facing member in spaced relation.

A further object of the invention is to provide a construction which eliminates the need for intermediate supporting members such as the furring strips which are employed by the known constructions for attaching the tiles to the wall or ceiling surfaces.

An additional object is to provide a sound absorbing unit having a perforated facing of the character described, which is secured to the wall or ceiling by an adhesive.

Other objects and advantages will be apparent from a consideration of theseveral embodiments of the invention shown in the accompanying drawings.

Fig. 1 illustrates in perspective a perforated metal pan facing member which is adapted to receive and be attached to a sound absorbing unit;

Fig. 2 is a sectional view taken along a'line indicated by line 2-2 of Fig, 1 after a sound absorbing unit has been inserted and attached to the metal pan;

Fig. 3 is a view showing the manner in which my improved sound absorbing construction may be applied to a wall or ceiling surface; I

Fig. 4 is a view of-a modification of the construction shown in the prior figures;

Figs. 5 and 6 are views of further modifications of my improved construction; I

Figs. 7 and 8 are views along line 'I'1 and 88 of Figs. 5 and 6 respectively and in the directions indicated by the arrows upon these figures;

Fig. 9 is a sectional view of a further modification of my invention showing a diilerent manner of supporting the tiles;

Fig. 10 is a perspective view of a portion of a metal pan which is adapted to contain a flexible sound absorbing unit;

Fig. 11 is a broken sectional view showing the assembly of the pan shown in Fig. 10 and 9. flexible absorbing unit;

Fig. 12 is a perspective view of a supporting member for maintaining the pan and absorbing unit in spaced relation;

Fig. 13 is a view showing a method of supporting the metal pans upon wood furring strips;

Fig. 14 is aview of portions of two abutting pans showing the manner of fitting them toget'her during installation;

Figs. 15 and 16 are perspective views of two additional modified forms of my invention;

Fig. 17 is a fragmentary view of a further modifled form of my invention;

I Fig. 18 is a front view of a bracket member which is used in the construction shown in Fig. 17 for uniting the sound absorbing unit and the facing in spaced relation.

In the construction shown in Figs. 1, 2 and 3, the facing unit, in the form of a pan 10, is pref- .erably made of thin sheet metal, with a multiplicity of small openings therein, but it may be made of any thin stiff foraminous sheet material such as vulcanized fibre sheets, bakelized sheets, veneered wood sheets and the like. Its marginal or edge portions 11 are turned up substantially at right angles to the body portion and a bevel 12 may be provided at the junction. The marginal portions are divided by slits into sections or tongues some of which, designated by numeral 13, are turned inwardly substantially parallel to the bottom of the pan and spaced therefrom. Others, designated by numeral 14, are bent outwardly at an angle to their former positions and have their end portions bent inwardly substantially at right angles. These sections or

tongues

13 and 14 are usually narrower than the remain-' ing sections 11 at right angles to the bottom of the pan, although this is not necessarily so. Similar tongues are provided at the opposite side of the pan, although it is shown before the slitting and bending has been performed. The formation of the pan into the desired shape may be ac complished by one or more operations of an automatic machine. After the pan is thus shaped the sound absorbing unit is placed therein and arranged to rest upon tongues 13.

For the form of construction which will be described first, sound absorbing unit 15 may be of any of the known porous tiles or board-like products which possess high sound absorbing properties and are sufliciently stiff or rigid to be self sustaining by which it is meant that they are able to retain their shape under the conditions to which the units are subjected. The material may be of a fibrous character such as a board of compacted felted fibers of wood or bagasse which may have holes therein, at right angles to the surface, or it may be stiffened felt such as hair felt or mineral wool bonded into a unit by means of a suitable binder such as starch or sodium silicate, or it may be a molded porous ceramic product comprising porous granular particles such as pumice stone, coke, or the like bonded together by means of plaster of Paris, Portland cement or the like. The above is given by way of example since the composition of the sound absorbing unit forms no part of the invention.

The sound absorbing unit 15 is of any suitable thickness, preferably about one inch and of an area such that it fits snugly within the upturned sides of foraminous pan 10, as shown in Fig. 2. The unit is placed in the pan where it rests at its marginal portions upon the supporting tongues or ledges 13. The tongues 14 are then bent inwardly until they are substantially in line with sections 11, the end portions of tongues 14 being thereby pushed or inserted into the edges of the sound absorbing unit 15, as shown in Fig. 2. The structure of said absorbing unit should be suillciently soft to permit the penetration of the hooks or inward projections of tongues 14 but at the same time should be sufliciently rigid to insure that it is firmly and positively locked in place, with a clearance between itself and the bottom of the pan, resulting in a unitary structure or sound-absorbing tile. Units of fibrous character are usually of proper texture and a suitable texturecan be obtained in ceramic units by proper choice and proportions of aggregate and binder. The tongues or ledges 13 are spaced a suflicient distance from the body portion of the metalpan so that irregularities in the bottom surface of the absorbing unit do not affect the light reflection from the exposed surface of the pan and so that paint or cleaning solutions applied to the pan do not reach the absorbing unit. This spacing need not be greater than onequarter inch. The height of the turned up edges on sections 11 is such that the latter do not reach the plane of the surface of the absorbing unit remote from the pan. In other words the sound absorbing material projects above the sides of the pan in which it is fitted.

The complete unit may be attached to a wall or ceiling surface by means of an adhesive which may be applied to the entire surface of the wall or ceiling or of the absorbing unit, or may be applied in spots or strips, if, the former is not of the tile, a more plastic adhesive may be used,

preferably one which retains its plasticity over a sufflcient period to permit the adjustment of the level of a group of tiles before the adhesive becomes set. A suitable adhesive 0! the latter character is one which comprises a mixture of gilsonite, asbestos fibers and solvent naphtha. This remains plastic for a considerable period of time but at the same time possesses tenacious adhering properties. After the adhesive is applied to the wall or the absorbing unit the tile is brought into position. Where the surface to which the structure is to be attached is relatively uneven, the preferred method is to apply the adhesive in spots 16 as shown in Fig. 3 and at appreciable thicknesses which may be up to one inch. For practical reasons the treatment usually is made upon the ceiling and after a section of the treatment has been installed and leveled there may still be irregularities in the level of some tiles where they abut adjacent tiles. Such irregularities may very conveniently be corrected from the floor by means of an instrument such as'is shown in Fig. 3 and which consists of a platform 17 mounted upon the end of a pole 18. The instrument is applied at the junction of the tiles and pushed upwardly until the low portions have been raised to the level of the others. With care or after the acquisition of skill, the instrument may also be used for initially applying the tiles to the ceiling 19 and leveling them.

.tion of the tabs.

In the construction shown in Fig. 2 I may supplement the means for securing the. absorbing unit and the pan together by applying an-adhesurfaces'of unit 15. It may be practicable in many instances to rely solely upon the adhesive and dispense with the hooks or inwardly extending projections upon tongues 14. The adhesive will project into the perforations of the pan and into the pores of the absorbing unit and provide a very efficient lock between the two; It is readily appreciated that the turned up sides of the foraminous pan contribute materially to the stiffness of the body portion thereof but in cases where sheet material of sufficient stiffness is used, portions of the turned up sides may be eliminated. Such constructions are shown in Figs. 4 and 17.

In the construction shown in Fig.4, in order to prevent lateral displacement of the absorbing unit the end-most sections 11 are not removed.

Tongues

13 and 14 are also retained but the re-,

mainder of the sides is removed down to the beveled edge 12, as shown. If the metal is removed below the top of the beveled portion, visible open gaps will result at the joints between adjacent tiles, which is undesirable. Furthermore, the loss in stiffness is not as great as it would be if the beveled portion were also cut away. The advantage gained by removinga portion of the sides 11 is that the absorbing unit is more readily inserted in the pan.

In the modification shown in Figs. 5 and 7, the foraminous pan 20 is formed with the sides 21 continuous, but incisions are made in said sides whereby tabs 22 are formed. The tabs may all be similarly oriented or some, as is illustrated by the tab 23, may be inverted with respect to the others. After the absorbing unit 14 is in place in the pan the tabs may be turned inwardly as illustrated in Fig. '7 whereby positive engagement between the pan and the unit is obtained. Figs. 6 and 8 illustrate a similar construction but in which a narrow strip of metal is cut away along the cut edges of the tabs to facilitate manipula- Fig. 7 shows the manner in which a tab 22 engages the absorbing-unit while Fig. 8 shows the manner in which an inverted tab 23 engages the absorbing unit. Figs. 7 and 8 also illustrate a different manner in which the absorbing unit may be supported in spaced relation to the body portion of the pan. A narrow rim or ridge 24 is formed upon the edges of the absorbing unit and is adapted to fit along the bevel 12 of the pan and upon the adjacent portion of the body of the pan. Ridge 24 may be an integral part of unit 14 as shown or it may be of separate material, such as metal, or it may tend to the opening 25 which is nearest the edge of the pan. If the absorbing unit covers any of the openings, variations in soiling conditions and light reflection occur at the surface of the I position to rest upon the bottom of pan 30.

tile as explained heretofore and non-uniformity of appearance results.

Ifit is desirable to support the construction by T-shaped furring strips in' the manner shown in said Norris Patent 1,726,500, this may readily be accomplished as shown in Fig. 9. Two opposite sides 26 of' each pan have the tongues 13 cut therefrom and the remainder may be substantially plane and continuous except for ears 2'! which are struck therefrom and adapted to rest upon supporting ledges 28. as described in said Norris patent. The other two sides may be formed as described heretofore in connection with Figs. 1 to 8. The absorbing unit in this case is made shorter than the pan in the dimension between sides 26 and is inserted and fastened in place in the ordinary manner between the other two sides of the pan. There is provided in this mannerga space between the two opposite edges of the absorbing unit'and the corresponding sides 26 of the pan. The tongues 13 of sides 26 may also assist in spacing the unit from the sides of the pan. These sides may be inserted between the ledges 28 of furring strip 29 which is adapted to be fastened to a wall or ceiling. The spaces between the edges of the absorbing unit and the sides 26 of the pan are occupied by the legs of the furring strip, as shown in Fig. 9. The lowermost portions of the legs of the furring strip are above and do not interfere with the tongues 13.

It may not be necessary, in many instances, to provide means for engaging the absorbing unit upon all sides of the pan. It may be sufficient to provide such means on two opposite sides only,

without sagging, when supported at opposite edges only. The invention is not limited to the use of this type of absorbing unit, however, and may be used in connection with a fiexible unit such as an ordinary soft hairfelt or balsam wool pad. Balsam wool is a product which comprises felted wood fibers. A sound absorbing unit of flexible character is usually less expensive and more efiicient as a sound absorber than a rigid unit. Figs. 10, 11, 12, 13, 14, 16 and 1'7 illustrate constructions suitable for use with flexible sound absorbing units. Any of the constructions shown in these latter figures are also suitable for use with rigid sound absorbing units.

In Figs, 10 to 14 the perforated metal pan 30 has tongues 31 turned inwardly from the sides 32 to form ledges or supports for the absorbing unit, which ledges are modified slightly from the supporting ledges described heretofore in that each is provided with an end portion 33 which is bent downwardly into a substantially vertical In this way said ledges are supported at both ends which may be desirable under some circumstances.

At the corners and at other points the sides of the pan have turned in flanges 34 which, as illustrated in Fig. 11, are adapted to fit over the marginal portions of the rearward surface of absorbing unit 35. Said flanges may be integral parts of the pan or may be spot welded or otherwise attached thereto. The absorbing unit may be supported centrally also or at as many points as necessary by supporting members such as small posts 36, each struck from a metal plate 3'7, serving as a head, and having pointed projections 38 punched upwardly at right angles thereto, the post or shank being semi-circular or otherwise suitably shaped and punched out in the opposite direction. The sharp projections serve to attach the spacing member to the absorbing unit, said spacing member resting on the surface of the pan and maintaining the pan and absorbingunit in spaced relation. Such a supporting member may be used also with the rigid type of absorbing unit if it is considered advisable. Flanges 34 may be secured to the contiguous surfaces of the absorbing unit by means of an adhesive, and the ledges 31 and the sides 32 of the pan may also be secured in like manner to the edges of the absorbing unit.

Flanges 34 may also serve to support the pans upon the wall or ceiling by means of adhesives such as are heretofore described. The flanges may be provided with perforations 39 of increased size to provide improved locking means for the adhesive. If it is desired to support the pans by means of furring strips such as wood strips 40, as illustrated in Fig. 13, flange sections 41 may be turned outwardly substantially at right angles from the sides of the pan, as shown more clearly in Fig. 14. Said sections 41 are provided with openings 42 through which they may be nailed or screwed to furring strips 40. The inwardly turned flange sections 34 serve to confine the absorbing unit as previously explained. Ordinarily the parallel furring strips extend in one direction only so that flange sections 41 need be provided upon only two opposite sides of the pan. The pans may be installed in such a manner that only one side of each pan need be fastened to the furring strip except in the case of the flrst row of pans. Fig. 14 illustrates how this may be done. Pan 43 may be fastened to furring strip 40 by means of one or more flanges 41. The furring strip is partially cut away in Fig. 14 and the absorbing units are removed in order to prevent interference with a clear illustration of the arrangement of the pans. After pan 43 is in place, pan 44 is slid into abutting relation with the former. During this operation flange section 45 of the pan 44 moves into position between furring strip 40 and the top edge of the side ofpan 43 and laterally between

flange sections

34 and 41 of the latter. Flange section 45 rests upon the edge-of the side of pan 43 and in this manner supports one side of pan 44. The flange sections may be arranged to occur at such points that they will interflt with the cooperating flange sections of adjacent pans to permit the desired pattern or arrangement of tiles upon the wall or ceiling surface. I

The construction shown in Fig. 15 is a modification of that shown in Fig. 1. Tongues 46 and 4'7, corresponding to

tongues

13 and 14 of Fig. 1, are punched out of the sides 48 of pan 49.

Tongues

46 and 47 do not extend the entire height of the sides of the pan, the upper edge being contions of the sides and into the body of absorbing unit 50. A very eflective attachment is made if staple 51 is of a size that it flts fairly tightly into the perforations. The staple may be treated prior to use with a thin fllm of a relatively slow setting glue or cement. By dipping it into an ordinary cement used for cementing laminations of bakelite, called bakelite cement, satisfactory results are obtained. A thin film is formed on the staple which sets slowly and unites the staple rigidly to the pan and the absorbing unit. The staples should be relatively long, that is, from one halfto one inch or more in length.

In the construction shown in Fig. 16, the hooked tongues are omitted and the top portions of the sides are turned inwardly to form flanges 52. The absorbing unit is adapted to flt between said flanges 52 and ledges 53. At the corners the flange of one side may be cut away to accommodate that of the adjacent side as shown at the left hand corner in Fig. 16 or the flanges may simply be overlapped as shown at the right hand corner in Fig. 16.

In Figs. 1'7 and 18 there is illustrated a form of construction which is adapted to effect a saving of material in connection with the manufacture of the facing member. The foraminous pan 54 has beveled marginal portions 55 but the marginal or side material stops at substantially the upper edges of said beveled portions. Provision for uniting pan 54 to sound absorbing unit 56, in spaced relation, is made in the form of brackets 5'7, shown separately in Fig. 1B. A tongue or ear 58 is punched into one end portion of the bracket and is bent substantially at right angles as shown in Fig. 1'7. The remainder 59 of the same end portion is bent in the same direction an amount equal to the angularity of beveled portion 55 from the vertical. End portion 59 of the bracket is fastened as by spot welding to the marginal portion 55 of pan 54. A number of such brackets may be similarly disposed at intervals along the margins of the pan. This operation may be done very rapidly by suitable spot welding machinery. Bracket 5'7 may be made of perforated metal scrap pieces of the same perforated pattern as occurs on pan 54 and by care in registering orplacing the bracket 57 onto pan 54, the perforations of bracket 5'7 will match perforations in pan 54. It is also planned to use perforated pans 54 where the beveled edges 55 are not perforated in which case no matching of holes would be considered. Sound absorbing unit 56 may then be placed upon supports 58 and the end portions 60 of the brackets be turned inwardly to engage the upper marginal portions of absorbing unit 56 and hold the latter in place. Portions 60 of the brackets ordinarily will provide enough surface to glue or cement the tiles to a wall or ceiling surface, and the adhesive may, in addition, be applied between the surface of the absorbing unit and the wall or ceiling. This type of construction is suitable for both flexible and rigid sound absorbing units.

This invention provides a construction which is particularly advantageous for treating vertical or nearly vertical surfaces. In many casesit may be preferable to treat wall rather than ceiling surfaces and lnsuch cases it is diflicult to obtain satisfactorily uniform results if the sound absorbing unit lies or is held loosely within the pan. The pan and unit may not retain a parallel relation and if the unit is flexible it may become wrinkled or folded and slump down into the lower portion of the pan. Such objections are obviated if the absorbing material, whether it be in flexible or rigid form, is secured to the pan to form a unitary tile.

In all of the illustrations the facing member is *shown with beveled comer construction. It is, of course, understood that the corners may be square turned or rounded just as well, this being largely a matter of design, to improve the appearance.

I claim:

1. In a sound absorbing construction comprising a thin self-sustaining foraminous pan having a body portion and sides and ,a relatively thick porous sound absorbing unit in said pan, means for spacing said unit from the body portion of said pan comprising tongues turned inwardly from said sides and spaced from said body portion.

2. In a sound absorbing construction comprising a thin self-sustaining foraminous pan ,having a body portion and sides and a relatively thick porous sound absorbing unit in said pan means for uniting said unit and said pan in fixed relation comprising tongues turned inwardly from said sides and engaging said unit.

3. In a sound absorbing construction comprising a thin self-sustaining foraminous pan having a body portion and sides and a relatively thick porous sound absorbing unit in said pan, means for spacing said unit from the body portion of said pan comprising ledges turned inwardly from said sides and spaced from said body portion, the end portions ofsaid ledges being turned downwardly and resting against said body portion.

4. As a new article of manufacture, a sound ab sorbing tile comprising a thin stiff foraminous facing member and a relatively thick porous sound absorbing backing member, said members being of substantially equal area and being united in fixed spaced relation, said uniting means comprising angular projections at the edges of said facing member, said projections engaging the adjacent edge portions of said backing member.

5. A sound absorbing construction comprising, in combination, a thin stiif self-sustaining foraminous facing member and a porous sound absorbing backing member, means for spacing said members apart comprising rearwardly disposed marginal extensions of said facing member,

said I extensions having angular projections against which the marginal portions of said backing member rest.

6. A sound absorbing construction comprising, in combination, a thin stiff self-sustaining foraminous facing member and a porous sound absorbing backing member, means for uniting said members in spaced relation comprising rearwardly disposed marginal extensions of said facing member, said extensions having angular projections, one group of said projections being spaced a greater distance than the other'group from said facing member, the marginal portions of said backing member being disposed between said groups of projections.

7. A sound absorbing construction comprising a thin self-sustaining foraminous pan having a body portion and sides, a relatively thick unit of sound absorbing material within said pan, the sides of said pan having tongues formed therein, at least some of said tongues being turned in- .wardly substantially parallel to and spaced from the body portion of said pan, said unit resting against said turned in tongues, said sides having angular flanges projecting from the edges thereof, some of said flanges being turned outwardly for attachment to a support, others of said flanges being turned inwardly for eng ing the surface 1 of said unit remote from said pan.

8. A sound absorbing construction comprising a thin self-sustaining foraminous pan having a body portion and sides and a relatively thick unit of sound absorbing material within said pan, ledges extending inwardly from said sides and spaced from said body portion, said unit resting group of said ledges, the difference between said spacings being substantially equal to the thickness of said absorbing unit, said absorbing unit flttin between said groups of ledges.

10. A sound absorbing construction comprising, in combination, a th n stiif self-sustaining foraminous facing member and a porous sound absorbing backing member, said facing member having marginal portions disposed at an angle to the surface thereof, said marginal portions engaging the edge portions of said backing member to unite said members with their adjacent surfaces in spaced relation.

11. A sound absorbing construction comprising, in combination, a thin, self-sustaining foraminous pan and a relatively thick porous sound absorbing unit within said pan, at least some of the sides of said pan having tongues formed therein, some of said tongues being turned inwardly substantially parallel to and spaced from the body portion of said pan, said unit resting against said turned in tongues, others of said tongues being attached to edge portions of said unit to unite said pan and said unit.

12. As a new article of manufacture, a sound absorbing tile comprising a thin stiff foraminous facing member and a relatively thick porous sound absorbing backing member, said members being of substantially equal area and being united in fixed spaced relation, said uniting means comprising rearwardly extending projections at the edges of said facing member, said projections being fastened to the adjacent edge portions of said backing member. I

13. A sound absorbing construction comprising, in combination, a perforated metal pan having a body portion and sides, and a unit of sound absorbing material within said pan, said unit being shaped laterally to fit snugly within said pan, at least two opposite sides of said pan having a plurality of tongues formed therein, one group of said tongues being turned inwardly substantially parallel to and spaced from said body portion, another group of tongues being turned inwardly at points further removed from said body portion, said tongues engaging the marginal portions of said unit tounite said pan and said unit in spaced relation.

some of said sections being turned inwardly substantially parallel to'and spaced from said body portion, said unit resting against said turned in sections whereby said unitis spaced from the bottom of said pan, at least some of the remainder of said sections engaging the edges ofsaid unit t unite said pan and said unit. v

15. A- sound absorbing construction, comprising in combination, athin stiifforaminous pan having a body portion and sides and a unit of sound absorbing material withinsaid pan, said unit being shaped laterally to fit snugly between the sides of said pan, the sides of said pan being attached to the adjacent edge portions of said unit, the points of attachment being so arranged as to space the body portion of said pan from the adjacent surface of said unit. a

16. A sound absorbing construction comprising, in combination, a thin self-sustaining foraminous facing member and a relatively thick porous backing member united thereto, means for spacing apart the adjacent surfaces of said members comprising projections at the edges of one of said members, said projections resting against the surface of the other of said members.

17. A sound absorbing construction comprising, in combination, a thin, self-sustaining foraminous rectangular pan and a relatively thick self-sustaining porous sound absorbing unit within said pan, two opposite sides of said pan having tongues formed therein and turned inwardly at an angle thereto, said tongues engaging the adjacent end portions of said unit to unite said pan and said unit, in spaced relation, the remaining two sides of said pan being adapted to engage a support, the adjacent edges of said unit being spaced from said support-engaging sides to accommodate the support.

18. A sound absorbing construction comprising, in combination, a thin, self-sustaining foraminous pan having a body portion and sides and a relatively thick porous sound absorbing unit in said pan, means for spacing said unit from the body portion of said pan comprising tongues turned inwardly from the sides of said pan substantially parallel to and spaced from said body portion, said unit resting upon said tongues, additional spacing means comprising a metal plate having pointed projections from one surface to penetrate said absorbing unit and a projection from the other surface to rest against said foraminous pan.

19. A sound absorbing construction for space enclosing surfaces comprising, in combination, a relatively thick unit of porous sound absorbing material, said unit being adapted to be adhesively secured to said surfaces and a thin, stiff foraminous facing member for said unit, said facing member being supported in spaced relation to said unit, said supporting means comprising angularly 1,992,509 being subdivided longitudinally into sections,

disposed edge extensions of said facing member, said extensions having angular projections at the ends thereof engaging the marginal portions of said unit.

20. A sound absorbing construction comprising, in combination, a thin self-sustaining foraminous pan, a relatively thick self-sustaining porous sound absorbing unit within said pan, a thin ridge member along the edge of the bottom surface of said unit, said ridge member resting against the body portion of said-pan, the sides of said pan having turned in portions for engaging the edge surfaces of said unit.

21. A sound absorbing construction, comprising in combination a. sheet of stiff material having a multiplicity of small holes therein, a unit of self-sustaining sound absorbing material and means unitary with the edges of said sheet and cooperating with. the edges of said unit for holding the two in fixed, spaced relation to each other.

22. In a building structure, the combination with a 'wall or ceiling surface of a room, of an exposed thin self-sustaining foraminous pan, mounted in spaced relation to said surface, said pan having a body portion and sides, a relatively thick porous sound absorbing unit in said pan and means for uniting said unit and said pan in fixed relation comprising tongues turned inwardly from said sides and engaging said unit.

23. In a building structure, the combination with a wall or ceiling surface of a room, of an exposed thin stiff foraminous facing member, mounted in spaced relation to said surface, and a relatively thick porous sound absorbing backing member, said members being of substantially equal area and being united in fixed spaced relation, said uniting means comprising angular projections at the edges of said facing member, said projections engaging the adjacent edge portions of said backing member.

24. In a building structure, the combination with a wall or ceiling surface of a room, of an exposed thin seif-sustaining foraminous facing member, mounted in spaced relation to said surface, and a relatively thick porous backing member united to said facing member, means for spacing apart the adjacent surfaces of said members comprising projections at the edges of one of said members, said projections resting against the surface of the other of said members.

25. In a building structure, the combination with a wall or ceiling surface of a room, of an exposed sheet of stiff material, mounted in spaced relation to said surface, and having a multiplicity of small holes therein, a unit of self-sustaining sound absorbing material and means associated directly with the edges of said sheet and engaging the edges of said unit for holding the two in fixed, spaced relation to each other.

KEIVIPER SLIDELL.