US3411605A

US3411605A - Acoustic conrol units

Info

Publication number: US3411605A
Application number: US626242A
Authority: US
Inventors: Moody L Coffman; Foey M Shiflet
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-03-27
Filing date: 1967-03-27
Publication date: 1968-11-19
Anticipated expiration: 1985-11-19

Description

Nov. 19, 1968 M. L. coFFMAN ET-AL 3,411,605

ACOUSTIC CONTROL UNITS Filed March- 27, 19.67 3 Sheets-Sheet 2 INVENTORS T| u Mopar oFF/WAN;

95 Paar /1/7. Pf/:457'

Nov. 19, 1968 M L, coFr-MAN ET AL 3,411,605

ACOUSTIC CONTROL UNITS Filed March 27. 1967 3 Sheets-Sheet 3 N gg E'LEvi F 'l :1T-i7 United States Patent O 3,411,605 ACOUSTIC CONTROL UNITS Moody L. Coffman, 1832 NW. 17th St., Oklahoma City, Okla. 73106, and Foey M. Shiflet, 1466 Tanglewood St., Abilene, Tex. 79605 Filed Mar. 27, 1967, Ser. No. 626,242 21 Claims. (Cl. 181-30) ABSTRACT OF THE DISCLOSURE Three-dimensional acoustic control devices which are movably mounted in a supporting lstructure adjacent, or forming part of, a wall or ceiling, and which include a sound reflecting surface and a sound absorbing surface. The devices are movable to expose to varying degrees, either the sound absorbing surface, or the sound reflecting surface, or selected portions of each of these surfaces. In lsome forms, the entire acoustic control device, including -both surfaces, is moved to different positions to vary the acoustic properties in a room in which the device is used. In other forms, either the sound absorbing or sound reflecting surface is moved and the other of two surfaces is maintained stationary.

Background of invention Field of the inventiont-The field of technology to which the present invention appertains is that of acoustics. More specifically, the present invention relates to devices and structures which may be located in enclosures, such as rooms and auditoriums, for the purpose of selectively varying the acoustic properties in such enclosures in order to adapt them for use at different times for the performance therein of programs varying widely in the frequency and intensity of sounds produced. I

Summary of the invention This invention provides movable structures which can be moved in a controlled manner to change the acoustic properties of a room by simultaneously varying either or both the surface and volume characteristics of a room or enclosure, and the sound reflectivity of at least a portion of the surfaces upon which the sound waves impinge. Broadly described, the acoustic control units of the invention comprise three-dimensional structures having at least one surface constructed of a sound reflecting material, and a different surface constructed of a sound absorbing surface and spaced from the surface of a sound reflecting material. One or both `of these surfaces, or the whole unit, is made movable with'respect to a supporting structure, such as a framework, or a wall, or a ceiling, with such movement being effected, in each case, in a manner so as to vary the surface area and reflectivity of the sound intercepting surfaces upon which the sound waves impinge en route to an audience. In al1 embodiments of the invention, the described movement effectively exposes more or less of either the sound reflecting or sound absorbing surface of the units, as may be desired, in order to alter in a predetermined manner the reverberation time of the sound in the room or enclosure.

In one embodiment of the invention, recesses are provided in the ceilings and/or walls and the acoustic control units are retractably mounted in such recesses and are each cross-sectionally dimensioned to fit fairly snugly in the respective recess when withdrawn or retracted thereinto. The units each have one or more side surfaces which are not exposed to the interior of the room when the units are retracted into their recesses and which are formed of a sound absorbing material. The -surface or surfaces of V3,411,605 Patented Nov. 19, 1968 ICC each unit which remains exposed when the unit is retracted is constructed of a sound reflecting material.

In another embodiment of the invention, the unit includes an indented or concave member, which, when mounted on a wall or ceiling, forms a depression or cavity therein. This member is either formed of, or lined with, a sound reflecting material. A pair of cooperating flaps or vanes are pivotally mounted adjacent the indented member so as to form a closure for the indented member when these vanes are pivoted into coplanar alignment, and to expose the sound reflecting interior of the indented member to varying degrees when pivoted away from the described position of coplanar alignment. The vanes are constructed of a sound reflecting material.

Yet another embodiment of the invention provides a stationary concave surface which is sound absorptive in character, and a mating elongated movable control element which may be oval, elliptical, ellipsoidal or circular in cross-section, but which, in any event, has a sound reflecting surface which is configured to mate with the stationary concave surface when the movable control element is moved into juxtaposition to the stationary concave surface. In this position, a second surface of the movable control element which is constructed of sound reflecting material is exposed to the interior of the room. The movable element is mounted and controlled in its movement so that it can be moved bodily toward or away from the stationary concave surface and simultaneously pivoted about a longitudinally extending axis.

An important object of the present invention is to provide improved acoustic control apparatus which can be used for effectively altering in a controlled fashion the acoustic characteristics of an auditorium or the like to adapt the `auditorium to a variety of types of programs or performances therein.

Another object of the invention is to provide an acoustic control unit which can be easily 4remotely controlled to impart predetermined acoustic properties to an enclosure in which the unit is employed.

Another object of the invention is to provide an acoustic control unit which can be relatively economically manufactured and maintained, and which is characterized in having a relatively long and trouble-free service life.

Additional objects and advantages of the invention will be perceived as the following detailed description of the invention is read in conjunction with the accompanying drawings.

Brief description of the drawings FIGURE 1 is a perspective view, partially in section, of one embodiment of the acoustic control unit of the invention as it appears when mounted in a ceiling.

FIGURE 2 is a perspective view, partially in section, of an acoustic control unit similar to FIGURE 1 but including one minor structural modification.

FIGURE 3 is a sectional View of another embodiment of the acoustic control unit of the invention as it appears when mounted in a ceiling. An alternate operative position of a movable part of the unit is shown in dashed lines.

FIGURE 4 is a plan View of the embodiment of the invention ldepicted in FIGURE 3.

FIGURE 5 is a view in elevation of another embodiment -of the acoustic control unit of the invention mounted on a wall of the room.

FIGURE 6 is a sectional view taken along line 6-6 of FIGURE 5.

FIGURE 7 is `a schematic, sectional view of the embodiment of the invention depicted in FIGURES 5 and 6 showing a Imovement control system which can be used with this embodiment of the invention.

FIGURE 8 is a plan view of the arrangement depicted in FIGURE 7.

FIGURE 9 is a sectional view taken alonge line 9-9 of FIGURE 7.

FIGURE 10 is a View in elevation similar to FIGURE lbut showing the acoustic control units depicted in FIGURE 5 as they appear when in a different operating position.

vFIGURE 11 is a horizontal sectional view taken through a wall and through a plurality of elongated, vertically extending acoustic control units movably supported adjacent the wall and constituting a modification of the embodiment of the invention depicted in FIGURES 5-10.

FIGURE 12 is a perspective view of another embodiment of the acoustic control unit of the invention, this embodiment being adapted for mounting in or adjacent the ceiling.

Description of preferrd embodiments 0f the invention In the drawings, systems or broad combinations comprising a plurality of subcombinations are designated in the drawings by reference numerals having lead lines with arrowheads. Subcombinations are designated by reference numerals which are underlined, and individual elements of structure are designated by plain reference numerals and lead lines.

In the embodiment of the invention depicted in FIGURE 1, the acoustic control units are mounted in a ceiling 12 and two of the units are illustrated for purposes of discussion. It will be understood from the following discussion that in actual usage, a considerable number of the control units 10 would be employed, and that they could also be mounted in the walls of an auditorium or room in similar fashion to their mounting in the ceiling. Each of the control units 10 includes an arcuate, preferably semicylindrical, member 14 which preferably is mounted in the ceiling to have one of its ends extending through, or into juxtaposition to, a wall. In some situations, however, the entire control unit-10 may be more suitably spaced outwardly from the wall in the ceiling, in which event an appropriate control system `differing to some extent from that which is hereinafter described will be utilized. It should also be pointed out that the member 14 need not necessarily be of a semicylindrical configuration, but can also be constructed in a U-shaped channel contiguration, or even in the crosssectional conguration of an inverted V.

The semicylindrical members 14 are mounted in the ceiling 12 so that the concavity 16 of each faces the interior of the room or, stated differently, toward the location of an audience in the enclosure in which the acoustic control units are located. Positioned beneath each of the elongated, semicylindrical members 14 are a pair of elongated flaps or vanes 18. The flaps or vanes 18 each have a pair of opposed longitudinal edges by which they are, in the illustrated embodiment, pivotally secured to a common, horizontally extending shaft 20 which is positioned below the central portion of the semicylindrical member 14, and in approximate alignment with the two lower and outer edges of the cylindrical member. The vanes 18 depicted in FIGURE 1 are characterized in having a transverse dimension such that, when they are pivoted to a position of coplanar alignment similar to the depicted full line position, they will extend across the concavity of the semicylindrical member 14, and beneath the free outer edges thereof, so as to completely close the concavity. As will be hereinafter explained in greater detail, the vanes 18 can be pivoted downwardly about the shaft 20 to expose the concave interior surface of the semicylindrical member 14.

Each semicylindrical member 14 is either constructed entirely of a material having relatively good sound absorbing characteristics, or may be formed as a rigid shell which is lined on its concave interior with a sound absorbing material. The vanes 18, by contrast, are constructed of a material having a relatively high degree of sound reiectivity.

For the purpose of actuating the vanes 18 in pivotal movement about the shaft 20, any suitable means for driving the vanes in pivotation may be utilized, and a relatively simple system is depicted in FIGURE 1. Here, the vanes are each suspended from cables 22 secured to the upper surfaces thereof adjacent an end of each of the vanes which is located inside the wall, or at least in a non-exposed position. The wall will necessarily be recessed or cut away in this case to accommodate the downward movements of the vanes. The cables 22 are extended over

suitable pulleys

24 and 26 and are reeved or wound about drums 28 carried on a shaft 30 which is driven in rotation by a suitable reversible motor 32. Actuation of the motor thus drives the shaft in rotation to retract the cables 22 and thus bring the vanes 18 upwardly to their position of coplanar alignment in which they close the concavity 16 of the semicylindrical member 14. Alternately, when the reversible motor 32 is driven in the reverse direction of rotation, the cables 22 are payed out, and vanes 18 move downwardly under gravitational influence to expose, in an increasing degree, the concavity 16 formed by the semicylindrical member 14, and thus permit more of the sound waves to impinge upon the sound absorbing material which lines the concavity.

In the operation of the acoustic control units depicted in FIGURE l, the reversible motor 32 may be actuated by an operator, or may be automatically controlled to respond to various types of sensing probes located in the interior of the room for the purpose of continuously sensing the acoustic quality at various locations within the room. The motor 32 will drive through a gear reducer 33. It should be pointed out that, since in almost all the acoustic control units of the invention, the movable control elements are moved so slowly in operation as to require the inclusion of gear reduction units between these elements and the driving motor, the gear reducer 33 has been included in all depicted drive systems. Retraction of the vanes 18 to their coplanar position so that the ceiling l2 is substantially monoplanar in overall geometric configuration, and so that a maximum sound reflecting surface area is exposed to the sound, effectively increases the reverberation time in the room, and thus improves its acoustic characteristics for the purpose of producing a musical or similar performance therein. On the other hand, in instances where an oral presentation, such as drama or public speaking, is to be performed in the room, it is desirable to have a relatively short reverberation time, and in this case, the acoustics are improved by pivoting the vanes 18 downwardly about the shaft 20 to varying degrees, depending upon the precise type of performance to be conducted in the room, and the overall geometry of the room.

A slightly modied version of the embodiment of the invention depicted in FIGURE 1 is illustrated in FIG- URE 2. Here, only the acoustic control unit per se is illustrated, and includes the semicylindrical member 14 which is identical to the same element used in the unit depicted in FIGURE 1. In this embodiment, however, the sound reecting vanes 40 which are provided have a lesser transverse dimension than the sound reflecting vanes 18 provided in the FIGURE 1 embodiment, so that their supporting shaft 42 and the vanes themselves may be located within the semicylindrical member 14, and aligned with the lower free edges of this member when the vanes 40 are in coplanar alignment as depicted in the full line position shown in FIGURE 2.

The modification eifected in the FIGURE 2 embodiment, as contrasted with that shown in FIGURE l, provides some advantage in that the sound reflecting vanes 40 may be pivoted either upwardly or downwardly to the two alternate dashed line positions for the purpose of modifying the acoustic characteristics of the room. Greater versatility and selectivity of control is provided, since there will be some difference in the effect on acoustics as between the result accomplished by the lowering of the vanes 40, and the result accomplished when they are retracted upwardly within the concavity 16. In either `instance, however, alteration in the acoustical properties of the roorn is effected in a substantial degree by changing the extent to which the sound waves being propagated in the room impinge upon sound reflecting as contrasted with sound absorbing surfaces, and also by changing in a controlled fashion, the surface geometry of the ceiling, and the total volume of the room.

It should be pointed out that a number of modifications can be effected in the embodiments of the invention depicted in FIGURES 1 and 2 without departure from the basic principles which are operative to achieve the objects sought by the invention. Thus, instead of being pivotally mounted on a common shaft, the sound reflective vanes can also be secured to two separate parallel shafts, and can either be pivoted individually or in synchronism. The particular type of control system used to actuate the vanes is not critical to the practice of the invention, and the cable drive system depicted in the drawings is merely one type of system which may be used for this purpose. For example, where two separate parallel shafts are used to amount the paired vanes of each acoustic control unit, it will be preferable in many instances to provide circular gears or gear segments adjacent one end of such shafts, and drive the shafts in rotation by the use of appropriate shafting and gearing, rather than to employ the cable system depicted in FIGURE 1.

In FIGURE 3 of the drawings, another embodiment of the acoustic control units of the invention is depicted. These units are also illustrated as mounted in a ceiling 44. The ceiling 44 has a plurality of spaced openings 46 formed therein for the accommodation of the acoustic control units which are designated generally by reference numeral 48. Suitable rigid housings 50 are provided above the ceiling 44 and over each of the spaced openings 46 therein to accommodate the acoustic control units 48 when they are retracted into the ceiling as depicted in the full line illusrations of the units in FIGURE 3. Each of the acoustic control units 48 depicted in FIGURE 3 is a hollow member formed as a generally rectangular parallelepiped which has side walls 52, which are either formed entirely of a sound absorbing material, or are at least covered on their outside surfaces with such material. A top wall 54 is optionally provided and may be formed of any suitable, relatively rigid material. A bottom wall 56 of each of the acoustic control units 48 is constructed of a sound reflecting material. The acoustic control units 48 are slidably mounted in the housings 50, and in operation can be extended from or retracted into these housings.

For the purpose of lowering the acoustic control units 48 from their respective housings 50, a cable 58 is passed through the top of each of the housings and connected to the top panel 54 of each of the acoustic control units. The cables 58 are extended over suitable sheaves or pulleys 60 and are connected to drums 62 carried by a shaft 64. The shaft 64 is driven in rotation by a reversible motor 66, and the connection of the cables58 to their respective drums `62 is effected so that as the shaft 64 is driven in one direction by the reversible motor 66, all of the acoustic control units 48 are simultaneously retracted into their respective housings 50. Rotation of the shaft 64 in the opposite direction by the reversible motor 66 permits the cables 58 to be payed out, and the acoustic control untis 48 to be extended downwardly from their respective housings 50. A plan view of the cable control system and its relationship to the several illustrative acoustic control units 48 depicted in FIGURE 3 is shown in FIGURE 4.

In the operation and use of thel acoustic control units depicted in FIGURE 3, the units may be disposed at any trol units are located is therefore at this time characterized in having a maximum sound reverberation time characteristic and is better adapted for the performance of music therein. By the lowering of the control units 48 to their dashed line positions, the smooth or monoplanar character of the ceiling 44 is broken up, greater surface area is presented for impingement by the sound, and a considerably larger amount of the total surface area exposed to the sound is constituted by a relatively highly sound absorbing material. Further than this, lowering of the control units 48 to their extended positions effectively decreases the total volume of the room or auditorium, and this reduction in volume also has the effect of decreasing sound reverberation time.

Another embodiment of the invention is illustrated in FIGURE 5. This embodiment of the acoustic control units of the invention is depicted as mounted vertically in a Wall designated generally by reference numeral 68. The wall 68 is depicted as extending from a floor 70 to a ceiling 72. As will be perceived in referring to the sectional view` of FIGURE 6, the wall 68 is provided with spaced semicylindrical recesses 74 which are lined with a sound absorbing material 76. The semicylindrical recesses 74 are spaced from each other along the wall by a distance which may be from about l to 11/2 or more times the diameter of each semicylindrical recess as measured along the exposed planar surface of the wall 68. The planar surface of the wall 68 between the semicylindrical recesses 74 is preferably covered with a sound reecting material 77.

In the operative position of the invention which is illustrated in FIGURES 5 and 6, a plurality of elongated, generally cylindrical movable control elements, designated generally by reference numeral 78 are supported in a vertically extending position so as to occupy the semicylindrical recesses 74 in the wall 68. The generally cylindrical control elements 78 each have a diameter such that the outer surface is complementary in configuration to the sound absorbing material 76 lining the respective recess 74 in the Wall in which it is located. In one type of construction which may be employed, each of the control elements 78 is hollow and is provided with a semicylindrical portion 80 Which is constructed of, or externally covered by, a sound absorbing material similar to the sound absorbing material 76 used to line the recess 74 in the wall 68. The complementary second semicylindrical portion of each control element 78 is designated by reference numeral 82 and is constructed of, or covered with, a sound reflecting material.

Extending coaxially through each of the generally cylindrical control elements 78 is a shaft 84 which is retained in the desired central location in the control element by a plurality of spokes or spider elements 86 so that rotation of the shaft 84 will effect rotation of the respective control element 78 about a longitudinally extending axis. As will be noted in referring to the sectional, partially schematic view of the control element illustrated in FIGURE 7, the shaft 84 of each of the control elements 78 extends -beyond the top end of the respective control element so as to pass upwardly through the ceiling 72.

The acoustic control units utilized in the embodiment of the invention depicted in FIGURES 5 and 6 are constructed so that two types of movement may be imparted to each of the generally cylindrical control elements 78. Thus, in addition to rotation of each of the `generally cylindrical control elements 78 about its longitudinal axis upon rotation of the shaft 84, each of the control elements 78 may be swung out of the respective semicylindrical recess 74 in the wall 68 and moved to a position adjacent the wall but intermediate the adjoining recesses. The mechanism and structure by which such movements are accomplished are best depicted in FIGURES 7-9.

As depicted in FIGURE 7, the upward extension of the shaft 84, after passing through the ceiling 72, passes through a slotted guide plate 90 which is positioned above the ceiling. The guide `plate 90 is arcuately shaped and has an arcuate guide slot 92 formed therein. The arcuate guide plate 90 projects horizontally inwardly `from the vertical plane of the inner surface of the wall 68, and functions to guide the movement of the shaft 84 as the respective generally cylindrical control element 78 which carries the shaft is moved bodily outwardly from the wall 68, and to the left as the several control elements 78 are depicted in FIGURES 5 and 6. The upper end of the shaft 84 has keyed thereto a driven gear 93 which, when the shaft 84 has been moved to the position depicted in dashed lines in FIGURE 8, meshes with, or engages, the teeth carried on one longitudinal edge of a rack bar 94. In different terms, the rack bar 94 is extended horizontally above the ceiling 72 in a position to engage the driven gear 93 when the driven gear has been moved to the outer end of the guide slot 92. The rack bar 94 is slidably supported in suitable guides to retain it in a position to engage the driven gear 93, and a suitable driving motor 96, shaft 97 and gear element 98 are provided as depicted in FIGURE 7 for engaging teeth 99 carried on the upper edge of the rack bar. The motor 96 is a reversible type so that it may be driven in rotation in either direction to cause a reciprocating motion of the rack bar 94.

Each of the generally cylindrical control elements 78 rests upon, and is supported by, a guide pan designated generally by reference numeral 100. The guide pans 100 are each arcuately shaped in a configuration which is generally complementary to the curvature of the guide plates 90, and includes a relatively thick metallic base plate 102, a pair of vertically extending

side plates

104 and 106, and a pair of vertically extending end plates 108 and 110 (see FIGURE 9). A base cap element 112 is secured to the lower end of each of the generally cylindrical control elements 78 and includes an annular metallic member 114 which has secured to the lower, generally planar surface thereof, a bearing race 116 which carries a plurality of ball bearing elements 118. The ball bearing elements 118 bear against the thick metallic base plate 102, and it is through the ball bearing elements that the weight of the hollow cylindrical control elements 78 is transmitted to the base plate 102.

For the purpose of moving the hollow, generally cylindrical control elements 78 outwardly through an arcuate path on the guide pans 100, a control arm 122 is pivotally connected to the upper end of the shaft 84 above the slotted guide plate 90 by means of a relatively loose tting clamp 124. Suitable keys or stops (not visible) are provided on the shaft 84 above and below the clamp 124 to prevent axial movement of the clamp along the shaft 84, but the clamp will turn freely about the shaft for a purpose hereinafter described. The opposite end of the control arm 122 from that which is pivotally connected to the shaft 84 is pivotally connected by a pin 128 to the free end of a piston rod 130 which reciprocates through a guide block 131 and is connected to a position 132 located in a suitable hydraulic cylinder 134. Hydraulic power fluid is supplied to an'd received from the cylinder 134 by means of a pair of

fluid conduits

136 and 138.

In the operation of the embodiment of the invention depicted in FIGURES -10, the control elements 78 are moved from the retracted positions depicted in FIGURES 5 and 6 to the extended positions depicted in FIGURE l0 in order to vary the acoustic properties of the room or enclosure in which they are located. Thus, for the performance of some type of program or presentation in which music is t0 be rendered, it will be desirable to position the control elements 78 as shown in FIGURES 5 and 6 so that the sound waves impinge upon surfaces which have a high degree of sound reflectivity. In this status, each of the generally cylindrical control elements is positioned in its respective recess 74 in the wall 68, and the portion 82 of the control element which is constructed of a sound reflecting material is exposed to the interior of the room. The planar wall surface 77 between the recesses 74 is also made of a sound reflecting material, and thus will reflect the sound and increase the reverberation time to better adapt the room for audience reception of musical performance.

When it is desired to alter the acoustics of the room so as to adapt it better -for the performance of an oral presentation, such as public speaking or drama, the control elements 78 can be moved bodily 4out of the recesses 74 in the wall 68 to the positions depicted in FIGURE 10 of the drawings. This is accomplished 'by actuating the hydraulic cylinder 134 so as to drive the piston 132 toward the end of the cylinder from which the piston rod 130 extends. This movement of the pistons 132 and piston rods 130 will in turn reciprocate the control arms 122 outwardly with respect to the wall 68, and the hollow, generally cylindrical control elements 78 will thereby be caused to move through arcuate paths as the base or cap elements 112 guide in the guide pans 100. The cylindrical control elements 78 are relatively light weight since they are of hollow construction, and need only present a wall material which is capable, in the case of one semicylindrical portion thereof, of a high degree of sound absorption, and in the case of the remaining semicylindrical portion thereof, of a high degree of sound reflectivity. The weight of the moving control elements 78 is carried by the ball bearing elements 118 which move smoothly on the supporting base plates 102 of the guide pans 100.

Either by limiting the travel or stroke of the piston rod 130, or by providing la stop which is contacted by the shaft 84, the arcuate, outwardly swinging movement of each of the control elements 78 is arrested at the outermost position depicted in FIGURE 10 of the drawings, and shown in dashed lines of the FIGURE 9. In this position of the control elements 78, each element is dispose-d outwardly from the wall 68, and is slightly spaced therefrom, and is located between adjacent pairs of the recesses 74. As each control element 78 reaches its limit of outward travel, the `driving gear 93 is placed in engagement with the teeth carried on the side of the rack bar 94. Further control of the acoustics in the room may then be effected by driving the rack bar 94 in reciprocation from the reversible motor 96 to cause each -of the generally cylindrical control elements 78 to be rotated about its respective pivotal axis as the shaft 84 to which it is keyed is caused to rotate. Thus, the extent to which either the sound absorbing portion of the sound reflecting portion 82 of each element 78, or both, are exposed to the interior of the room, and thus to impingement thereon of the sound waves, can be varied in a controlled manner to finally tailor the acoustic properties of the room as may be desired, and to adapt the room to any type of performance which may be carried out therein.

Another embodiment of the invention is shown in section in FIGURE 11. The general principles of operation which are employed in utilizing this embodiment of the invention are quite similar to the principles employed in the operation of the embodiment depicted in FIGURES 610. Different control effects can, however, 'be obtained through the use of the system depicted in FIGURE 1l. In this figure, a horizontal section through a portion of a wall 142 is illustrated, and the wall is either constructed of, or covered on its internal surface by, a sound reflecting material 144. The exposed or internal surface of the wall 142 is of a scalloped configuration so4 that a plurality of troughs or depressions 146 are provided in contiguous relationship to each other.

Mounted adjacent the wall are a plurality of elongated, generally ellipsoidally cross-sectioned acoustic control elements designated generally by reference numeral 148. The acoustic control elements 148 are preferably of hollow construction and are provided with one side or surface 150i which is characterized in having a high degree of sound absorptive ability, and a second side or surface 152 which is of relatively high sound reflectivity. `Each of the control elements 148 has a shaft 154 which extends eccentrically therethrough from the top of the control element to the bottom and is positioned more nearly adjacent one transverse edge of the control element than the other. Each shaft 154 is secured to the sound reflecting and

sound absorbing portions

152 and 150, respectively, of the respective control element 148 by suitable braces 158.

The control elements 148 depicted in FIGURE l1 of the drawings are actuated similarly to the control elements 78 depicted in FIGURES 5 1()` and hereinbefore described. Thus, suitable supporting structure (not illustrated) is provided beneath each of the control elements 148, and they are supported thereon by suitable bearing elements. Means is provided (not shown) for moving each of the ellipsoidally cross-sectioned control elements 148 bodily -away from the wall 142 so that the control elements are moved out to the positions occupied by the two control elements 148 shown in the right hand portion of FIGURE 1l. It will be perceived that, in this instance, because of the eccentric location of the shaft 154, the control elements 148 need not be moved through an arcuate path, but may be Imoved directly away from the wall 142 by a sufficient distance to permit free pivotation of the respective `control element about its shaft. The shafts 156 can then be driven in rotation to bring the control elements 148 to any desired position intermediate that shown as occupied by the right control element `depicted in FIGURE 1l, and that occupied by the left control element.

It will be observed that when all of the control elements 148 are retracted to their position nearest the wall 142 so that their sound absorbing surfaces 150 are in abutting contact with the depressions 146 in the wall, an uninterrupted surface of sound reflecting material formed by the portions 152 of the adjacent, aligned control elements is presented to a sound source within the room for impingement of the sound waves thereon. When the control elements 148 are moved outwardly and pivoted about their eccentrically positioned shafts 154 to varying degrees, however, a small to quite large sound absorbing surface can be interposed in the path of the sound waves. Large variations in surface area geometries can also be obtained by these movements of the control elements 148.

FIGURE 12 depicts yet another embodiment of the invention which is specifically adapted for mounting in a ceiling. Here, the acoustic control unit includes a stationary section 160 which may optionally be made as a separate member attachable to, or mountable in, the ceiling, or may be made an integral part of the ceiling. The stationary section 160 is provided with an arcuately shaped surface 162, and the entire stationary section may be made of a sound absorbing material, or, alternately, the surface 162 may be lined or covered with such a material. The stationary section 160 is mounted in the ceiling, or formed as a part thereof, so that the arcuately shaped surface 162 faces downwardly in the room. Of

course, in an actual arrangement, a number of the acoustic control units are usually mounted in the ceiling and their spacing and positions relative to each other are determined by the requirements of a particular set of prevailing environmental conditions, such as the geometry of the auditorium or room, the types of performances which it is contemplated may be rendered therein, and the degree of control of the acoustic characteristics of the room which it may be desired or necessary to achieve.

Suspended on a pair of

cables

164 and 166 immediately below the stationary section is a movable control element designated generally by reference numeral 168. The movable control element 168 is preferably formed as a hollow member having an arcuate upper surface which is complementary in configuration to the arcuate, generally concave surface 162 of the stationary section 160, and a lower surface 172 which is arcuately shaped across its transverse dimension and joined at its longitudinal edges to the upper surface 170. The upper surface 170 of the movable control element 168 is formed of a sound absorbing material, and the lower surface 172 thereof is formed of a sound reflecting material.

It will be noted in referring to FIGURE l2 that the

cables

164 and 166 are attached to opposed end faces 174 of the movable control element 164 at horizontally spaced points. Each of the

cables

164 and 166 is wound about

drums

176 and 178, respectively, which are keyed to shafts and 182 driven by

reversible motors

184 and 186.

In the operation of the embodiment of the invention depicted in FIGURE 12, the stationary sections 160 are mounted in or form a part of a ceiling, and presents to the audience below, a body having concavities formed therein by the arcuate surfaces 162 of the stationary section. In one operative position, the

cables

164 and 166 may be wound upon their

respective drums

176 and 178 so as to draw the movable acoustic control element 168 into contact with the stationary section 160. When this is accomplished, the sound absorbing material which covers the surface 162 is mated with, and abuts against, the upper surface 170 of the movable control element 168 so that none of the sound absorbing material is exposed for impingement thereon by sound waves. Rather, the sound reflecting lower surface 172 of the movable control element 168 is the only surface of the acoustic control unit which is exposed to the sound waves, and accordingly, the reverberation time is increased and the room is better adapted for the performance of music. When a speaking performance is to take place in the room or auditorium, the

cables

164 and 166 may be unwound from their

respective drums

176 and 178 to bodily lower the entire movable control element 168 away from the stationary section 160, and thus increase the total surface area upon which sound can impinge, thus decreasing the reverberation time. This movement of V,the movable control element 168 also has the effect of exposing to the sound waves a greater surface area constructed of sound absorbent material, and thus effects a further decrease in reverberation time. Finally, the amount by which the

cables

164 and 166 are payed out from their

respective drums

176 and 178 may be differed, so that, effectively, the movable control element 168 is rotated about an axis which extends between the points of connection of an aligned pair of the

cables

164 and 166 as this pair of cables is lowered to a lesser degree than the other pair of cables. By this rotational motion, a greater exposure of either the upper surface 170 or the lower surface 172 of the movable control element 168 to the sound waves may be accomplished, `and thus further selectivity in reverberation time characteristics can be attained.

From the foregoing description of the invention, it will be perceived that the invention provides .an improved system for tailoring the acoustics of an auditorium or other enclosures so that the same location may be used at different times for the performance of programs which require widely differing acoustic properties in the room or auditorium for optimum audience reception. The acoustic control units of the invention are relatively simple in construction, and do not require expensive materials for their fabrication. Moreover, the moving parts of the units can be operated in the required movements without any necessity for complicated delicate actuating systems. Each of the acoustic control units is characterized in providing a wide selection of positions which may be utilized to provide a great variety of acoustic properties in the room or enclosure in which the units are used.

The embodiments of the invention which have been described in the foregoing description all illustrate the incorporation of certain basic principles of acoustic control which constitute the basis of the invention, and it will be readily perceived by those skilled in the art that certain modifications and changes could be effected in the disclosed embodiments without departure from these principles. All changes and modifications of this type which continue to rely upon the basic principles of the invention as herein set out are deemed to be circumscribed by the spirit and scope of the invention, except as the same may be necessarily limited by the appended claims or reasonable equivalents thereof.

What is claimed is:

1. An acoustic control unit comprising:

a three-dimensional structure having a sound absorbing surface and a sound reflecting surface, a first portion of said three-dimensional structure being stationary and carrying one of said surfaces, and a second portion of said three-dimensional structure being movable relative to said first portion and carrying the other of said surfaces so that said sound reflecting surface is moved relative to said sound absorbing surface;

a supporting structure for mounting the three-dimensional structure at a peripheral portion of an enclosure in which sound is to be produced, said supporting structure and one of said surfaces of said three-dimensional structure being unmoving with respect to each other; and

means for moving at least one of said surfaces relative to said supporting structure so as to expose by such movement, varying surface area amounts to one of said surfaces to the interior of the enclosure, and to vary the total surface area exposed to impingement thereon by sound waves produced in the enclosure.

2. An acoustic control unit as defined in claim 1 wherein said first portion defines a recess, and said second portion comprises vane means pivotally mounted on said supporting structure and movable from a position to close 'said recess to a position in which said recess is open.

3. Anv acoustic control unit as defined in claim 2 wherein said vane means includes a pair of vanes mounted for rotation about a common axis or parallel axes of rotation, said vanes being pivoted by said moving means into coplanar alignment to extend across the opening to, and close, said recess, and being pivotal away from the position of coplanar alignment by said moving means to open said recess.

4. An acoustic control unit as defined in claim 2 wherein said recess is lined with a sound absorbing material, and wherein said vane means comprises a pair of vanes constructed of a sound reflecting material and positioned to close said recess when said vanes are in coplanar alignment.

5. An acoustic control unit as defined in claim 4 wherein said vanes are dimensioned to permit them to be pivoted into said recess.

6. An acoustic control unit comprising: Y

a three-dimensional 'structure having a sound absorbing surface and a sound reflecting surface;

a supporting structure for mounting the three-dimensional structure at a peripheral portion of an enclosure in which sound is to be produced wherein said supporting structure includes a sound affecting surface which differs substantially in its ability to reflect sound from the sound refiecting ability of one of said sound absorbing and sound reflecting surfaces carried by said three-dimensional structure,

and wherein said three-dimensional structure is mounted in said supporting structure for movement from a first position in which said three-dimensional structure is in juxtaposition to said sound affecting surface and obscures it from sound waves originating in the enclosure, and said one of said sound absorbing and 'sound refiecting surfaces which differs from said sound affecting surfaces in its ability to reflect sound is exposed to the interior of the enclosure, to a second position in which said three-dimensional structure is spaced from said sound affecting surface, and said sound affecting surface is exposed to permit the impingement of said sound waves thereon, said entire three-dimensional structure being movable relative to said supporting structure, and carrying both the sound absorbing and sound reflecting surfaces in such movement; and

means for moving at least one of said 'surfaces relative to said supporting structure so as to expose to the interior of the enclosure by such movement, varying surface area amounts of one of said surfaces, and to vary the total surface area exposed to impingement thereon by sound waves produced in the enclosure.

7. An acoustic control unit as defined in claim 6 wherein said three dimensional structure is a closed geometric figure in cross-section, and is elongated, and wherein said moving means includes means for rotating said three-dimensional structure about a longitudinal axes after said three-dimensional structure is moved to a position spaced from said sound affecting surface.

8. An acoustic control unit as defined in claim 7 wherein said sound affecting surface is concave in cross-sectional configuration and is constructed of a sound absorbing material.

9. An acoustic control unit as defined in claim 7 wherein said moving means includes a hydraulic piston and cylinder assembly for moving said three-dimensional structure away from said supporting structure, and means for guiding said three-dimensional structure through an arcuate path during its movement away from said supporting structure.

10. An acoustic control unit as defined in claim 7 wherein said rotating means includes a motor and gearing drivingly connected to said three-dimensional structure.

11. An acoustic control unit as defined in claim 6 wherein said supporting structure is elongated and has an elongated recess formed therein, said recess being of uniform cross-sectional dimension over its length and forming said sound affecting surface, and wherein said one surface which differs from said sound affecting surface is complementary in configuration to said recess.

12. An acoustic control unit as defined in claim 11 wherein said recess is semi-cylindrical in configuration, and said three-dimensional structure is cylindrical in configuration.

13. An acoustic control unit as defined in claim 11 wherein said three-dimensional structure is generally ellipsoidal in cross-sectional configuration.

14. An acoustic control unit comprising:

a three-dimensional structure comprising a plurality of sides carrying sound absorbing surfaces and an additional side carrying sound reflecting material;

a supporting structure for mounting the three-dimensional structure at a peripheral portion of an enclosure in which 'sound is to be produced, said supporting structure defining a cavity sized to receive said three-dimensional structure, and said three-dimensional structure being positioned in said cavity to extend said side carrying sound reflecting material across a major portion of the opening to 'said cavity;

means for moving the entire three-dimensional structure relative to said supporting structure to expose by said movement, varying surface area amounts of one of said surfaces to the interior of the enclosure, and to vary the total surface of the area exposed to impingement thereon by sound waves produced in the enclosure, said moving means including means connected to said three-dimensional structure for moving the three-dimensional structure from a first position in which said three-dimensional structure is retracted into said cavity with said additional 'side extending across a major portion of the opening to the cavity, to a second position in which said three-dimensional 'structure extends at least partially from said cavity, and the sound absorbing surfaces on a plurality of sides are at least partially exposed.

15. An acoustic control unit as defined in claim 14 wherein said cavity is substantially rectangular in vertical and horizontal cross-section, and wherein said three-dimensional structure is a right parallelepiped retractable into said cavity and extendable therefrom, said right parallelepiped three-dimensional structure having said additional side extending normal to said plurality of sides.

16. An acoustic control unit comprising:

a three-dimensional structure having a sound absorbing surface and a sound reflecting surface;

a supporting structure for mounting the three-dimensional structure at a peripheral portion of an enclosure in which sound is to be produced, said supporting structure defining a cavity which is lined with a sound absorbing material, and wherein said three-dimensional structure has a portion which is of complementary geometric configuration to said cavity and carries said sound absorbing surface;

means for moving the entire three-dimensional structure relative to said supporting structure so as to expose by such movement, varying surface area amounts of one of said surfaces to the interior of the enclosure, and to vary the total surface area exposed to impingement thereon by sound waves produced in the encolsure, and said moving means including means for moving the three-dimensional structure into and out of said cavity with the complementary geometric configuration portion of said three-dimensional structure being placed in contacting registration with said cavity lining when 'said three-dimensional structure is moved into said cavity.

17. An acoustic control unit as defined in claim 16 wherein said cavity is semicylindrical in configuration, and said three-dimensional structure is cylindrical and said sound absorbing and sound reflecting surfaces are of semicylindrical configuration.

18. An acoustic control unit as defined in claim 16 wherein said three-dimensional structure is an elongated member of uniform ellipsoidal cross-section, and wherein said cavity is complementary in configuration to a portion of the arcuate outer peripheral surface of said elongated member.

19. An acoustc control unit comprising a cylinder having a first arcuate surface of sound absorbing material and a second arcuate surface of sound reflecting material, said first and second surfaces being joined along longitudinal edges to form a closed geometric configuration in cross-section;

a supporting structure for mounting the cylinder at a peripheral potrion of an enclosure in which sound is to be produced, said supporting structure having a semi-cylindrical recess formed therein and dimensioned to receive and accommodate said cylindrical three-dimensional structure, said recess being lined with a sound absorbing material; and

means for moving said cylinder relative to said sup- :porting structure so as to expose by such movement, varying surface area amounts of one of said surfaces to the interior of the enclosure, and to vary the total surface area of said cylinder which is exposed to impingement thereon by sound waves produced in the enclosure.

20. An acoustic control unit comprising a three-dimensional structure having at least one side carrying a sound absorbing surface and having at least one additional side carrying sound reflecting material;

a supporting structure for mounting the three-dimensional structure at a peripheral portion of an enclosure in which 'sound is to be produced, said supporting structure defining a cavity sized to receive said three-dimensional structure so that said side carrying sound reflecting material extends across a major portion of the opening to said cavity;

means for moving the entire three-dimensional structure relative to said supporting structure and from a first position in which said three-dimensional structure is retracted into said cavity with said side carrying sound reflecting material extending across a major portion of the opening to the cavity, to a second position in which said three-dimensional structure extends at least partially from said cavity, and the sound absorbing surface is at least partially exposed, whereby as a result of such movement, the total surface area of said three-dimensional structure which is exposed to impingement thereon by sound waves produced in the enclosure is varied.

21. An acoustic control unit comprising:

a supporting structure for mounting the three-dimensional structure at a peripheral portion of an enclosure in which sound is to be produced, said supporting structure having an opening therein accommodating at least a portion of Said three-dimensional structure, said three-dimensional structure being mounted in said supporting structure so that said sound reflecting surface of said three-dimensional structure extends across a substantial portion of said opening for exposure to a source of sound in said enclosure;

moving means connected to said three-dimensional structure for moving the three-dimensional structure from a first position in which said three-dimensional structure is retracted into said opening with said sound reflecting surface extending across a substantial portion of the opening, to a second position in which a relatively greater portion of said three-dimensional structure is positioned in said enclosure in Which sound is to be produced than is positioned therein in said first position, and in which second position the sound absorbing surface of said threedimensional structure is at least partially positioned in said encolsure and exposed to the source of sound therein, said moving means including a motor and gearing drivingly connected to said three-dimensional structure for moving said three-dimensional structure between said first and second positions.

References Cited UNITED STATES PATENTS 1,825,465 9/ 1931 MacDonald 181-30 2,224,651 12/ 1940 Jacobs 181-33 2,277,983 3/1942 Jacobs 181-33 .2,590,204 3/ 1952 Phillips 181-33 2,855,039 10/1958 Gross 181-33 3,049,190 8/1962 Coffman 181-30 XR FOREIGN PATENTS 1,333,063 6/1963 France.

375,726 6/ 1932 Great Britain.

70 RO'BERT S. WARD, JR., Primary Examiner.