US2935151A - Acoustic absorber - Google Patents

Acoustic absorber Download PDF

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Publication number
US2935151A
US2935151A US534958A US53495855A US2935151A US 2935151 A US2935151 A US 2935151A US 534958 A US534958 A US 534958A US 53495855 A US53495855 A US 53495855A US 2935151 A US2935151 A US 2935151A
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United States
Prior art keywords
acoustic
perforations
ceiling
light
openings
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US534958A
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English (en)
Inventor
Bill G Watters
Jordan J Baruch
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Bolt Beranek and Newman Inc
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Bolt Beranek and Newman Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bolt Beranek and Newman Inc filed Critical Bolt Beranek and Newman Inc
Priority to US534958A priority Critical patent/US2935151A/en
Priority to DK323256AA priority patent/DK108542C/da
Application granted granted Critical
Publication of US2935151A publication Critical patent/US2935151A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V33/00—Structural combinations of lighting devices with other articles, not otherwise provided for
    • F21V33/006—General building constructions or finishing work for buildings, e.g. roofs, gutters, stairs or floors; Garden equipment; Sunshades or parasols
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B9/00—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation
    • E04B9/34—Grid-like or open-work ceilings, e.g. lattice type box-like modules, acoustic baffles
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2103/00—Elongate light sources, e.g. fluorescent tubes

Definitions

  • the present invention relates to apparatus for absorb ing acoustic ene igy, and more particularly absorbing acoustic energy while permitting the transmission of light.
  • a ceiling light fixture may comprise, for example, a fluorescent lamp disposed within a reflector and covered by a translucent glass or other lightdiffusingmaterial.
  • Conventional acoustically absorbent materials have been disposed between the reflectors of adjacent light fixtures,- forrning a false ceiling.
  • This arrangement is subject to the principal disadvantage that the regions between the light fixtures along which the acoustically absorbent material is disposed do not permit the transmission of light so that large areas of thefalse ceiling remain unilluminated. If a large degree of acoustic absorption is to be produced, therefore, the amount of illumination available from the ceiling light fixtures is decidedly limited.
  • the sizable translucent glass or other covers for. the fixtures reflect appreciable sound energy; directed. thereupon.
  • bafiies of rigid a s rptive ma i a sfroni the screen.
  • the baffles may also be replacedby acoustically absorbent fibrous material housed in perforatedcontainers.
  • the carrier member may then be utilized as a unitary device to serve both as a light-transmitting member and as an acousticabsorbin'g member without the necessity for additional layers of sound-absorbing. material or sound-absorbing linings'dispos'ed upon surfaces" such as walls, ceilings, or th'elike.
  • H V H Ari object of the present invention therefore, is to provide such a unitarylight-transmitting acoustically absorbent carrier member.
  • An additional object is to provide anew and improved acoustic absorberf
  • Fig. l is a perspective view of a preferred embodiment of the inventionadaptedfor use as a false ceiling
  • Fig. 2 is a fragmentary section, taken upon the line 2-4 of Fig. 1, looking in the direction of the arrows, but drawn upon an enlarged scale;
  • Fig. 3 is a graph illustrating the design considerations underlying the present invention.
  • Fig. 4 is afur'ther. graph illustrating the performance of the invention.
  • Fig. 5 is a fragmentary view of a modification.
  • Conventional fluorescent or other light sources or fixtures 1 are shown suspended at 3 from a fixed ceiling 5.
  • struts 7 that are terminally secured by vertical projections 11 to vertical elements 12 of horizontally extending supporting beams 9, illustrated as,T-shaped in cross section.
  • supported members 15 preferably of light-transmitting, acoustically absorbing material constructed in accordance with the present invention, and. thus maintained in spaced Y relation with the ceiling 5.
  • the member 15 comprises a relatively rigid light-transmitjting carrier member having, a plurality of spaced openings, perforations or apertures 17 passing therethrough between the upper and lower surfaces of the member.
  • the term perforations is hereinafter employed in its broad sense to embrace any kind of opening or aperture.
  • spanner member 15 may be translucent. If transparency is desired, on the other hand, the member 15 may be transparent. Many other desired esthetic effects may be obtained through corrugation, embrossing or otherwise decorating the carrier member 15, as desired.
  • plastics such as styrene, polystyrene, polyester resins, and relatively rigid polyvinyl plastics such as polyvinyl chloride and acetate, known as Vinylite, to mention but a few. It is, of course, well known that these and other plastic materials can be fabricated to provide light-transmission by diffusion, translucency or transparency, to any desired degree. In addition, it is also well known that such materials can be fabricated with the necessary perforations 17 and with any desired degree of corrugation, embossing or other decorative or ornamental surfacing.
  • a carrier member 15 utilized in themanner shown in Fig. 1 therefore, acoustic energy rising upward in the room would merely reflect back downward into the room from the unperforated portions of the member 15. That acoustic energy which entered improperly designed perforations 17, moreover, would pass through the same into the bounded airspace region between the member 15 and the fixed ceiling 5. This energy would be reflected back downward from the ceiling 5 and some of it would pass back through the perforations 17 into the room below. While such a carrier member could provide the required light-transmission and could be sulficiently rigid to be suspended as a false ceiling between the beams 9, it could not thus serve to quiet the sounds in the room below the ceiling.
  • the perforations are properly designed, as the acoustic energy is forced to pass through the openings 17 of the carrier member 15, the acoustic energy will be dissipated in view of the viscous friction and other impeding effects of the openings or perforations.
  • the openings are of the size ordinarily used in other types of sound absorbing ceilings, however, such as openings of the order of A of an inch in diameter, more or less, relatively closely spaced from one another, then the resistance presented to the incident sound energy in the audible frequency range is too low to be effective to dissipate sound energy through the action of the perforations alone.
  • the carrier members 15 are incapable of acting as effective wide-frequency-band absorbers.
  • the corresponding optimum relationship between the interdependent variables r, n and d has been found to be:
  • Equation 2 The optimum design curve represented by Equation 2 is plotted at A in Fig. 3.
  • the optimum perforation crossdimension 2r should be substantially 8 mils.
  • a larger ratio n/d l00, would require performations of smaller cross-dimension of substantially 4 /2 mils.
  • a small ratio n/d 0.1, on the other band, would necessitate the utilization of much larger perforations of substantially 24 /2 mils in cross-dimension.
  • Equation 2 would, in theory, hold for any size perforation, it has been found, in practice, that there are upper and lower commercially useful limits.
  • the lower limit of perforation cross-dimension is determined not only by the feasibility of effecting minute perforations in the member 15, but, also, by the susceptibility of the perforations to clogging by dust, dirt and other particles,
  • the clogging difficulty may, in part, be mitigated against by blowing air through the perforations as, for example, with the aid of a blower duct in the space between the member 15 and the ceiling 5.
  • a lower limit in perforation cross-dimension of substantially 2 mils is shown in Fig. 3.
  • the upper limit is determined by the appearance of an esthetically unattractive pinholing effect that results when the perforations are sufliciently large to permit viewing of the light fixtures therethrough. It so happens that poor high-frequency acoustic-energy absorption occurs, also, when the perforations are too large.
  • an upper limit in the perforation cross dimension of about 40 mils is illustrated.
  • Equation 2 The invention is also of considerable utility in regions on either side of the optimum relationship of Equation 2 and curve A.
  • the invention is inoperative, however, both too far to the right, in the region of ordinary perforated acoustic facings, and too far to the left, in the region of sound impervious materials.
  • the limiting curves of 0:0.18 and 0:18 are shown at B and C, respectively, in Fig. 3.
  • the equations represented by the respective curves B and C are given as follows:
  • Equations 2, 3, and 4 be represented by the letter K, then the above range, shaded in Fig. 3, involves values of K of from substantially 2.39 to substantially 4.39.
  • the absorption coeflicient of this sheet is plotted along the ordinate, in Fig. 4, as a function of the acoustic-energy frequency, plotted along the abscissa.
  • the dash-line curve iicient and the solid line curve represents actual measurements, 'of. acoustic-energy absorption as a function of frequency.
  • the frequency of this peak can be lowered, if desired, by in creasing the acoustic mass reactance of the holes, but such a decrease in the peak frequency is obtained only at the expense of lowering the degree of absorption, especially at frequencies away from the peak frequency. Since, moreover, the mass reactance increases with increasing frequency, a sheet which is suitable for use with a deep air space for low-frequency absorption may not operate well with a shallow air space as a high-frequency absorber.
  • the invention has been illustrated and described in connection with its application as a false ceiling for a room or other space, it is to be understood that this is by way of illustration only, and that the invention may be used in any other place where it is desired to employ its acoustical absorption properties, such as along a wall, a floor or any other surface, including even as lamp or lighting shades or fixtures. It is also to be understood that the absorber need not be formed in the substantially planar form illustrated. It may be fabricated in any desired shape or, after fabrication, it may be post-formed into the desired configuration. The perforations or openings may be integrally formed or they may be subsequently punched as with the aid of a plurality of needles and the like.
  • the perforations be similar and substantially uniformly distributed, deviations can, in practice, be tol a d. in which event the values of the var ou parame e s o Equa 1 th ou 4 m ybe ave a e alues,- lu v ew of its P o io for acoustic ,resistiyity through the use of the proper number and s zeo a Pa sa es orperfc at o moreover, the
  • the invention is useful for its acoustic-absorbing properties alone, as in many applications where light-transmission is not required.
  • the member 15 may then be opaque, if desired.
  • the carrier medium may also be formed as shown in Fig. 5 by weaving together, as in a cloth, small threads or rods 20 of material, such as plastic. These threads may or may not be translucent, depending upon the desired end. They can readily be formed by saturating fibrous glass threads with a plastic material, such as polyester resin. The perforations or openings in the medium, as previously described, would in this case be formed by the interstices 22 between the threads.
  • a structure for absorbing sound waves comprising a perforated sheet supported adjacent and spaced from said wall surface, said sheet having substantially the following relationship between the thickness d of the sheet, expressed in thousandths of an inch, the number n of perforations per square inch of surface of the sheet and the half-cross-dimension r of the perforations, expressed in thousandths of an inch:
  • k is a constant lying within the range of from substantially 2.39 to substantially 4.39 and wherein the cross-dimension of the perforations lies within the range of from substantially 2 to substantially 40 thousandths of an inch, the sound waves being constrained to pass through said sheet to gain access to the space between said sheet and said wall surface, and the sheet per se having the property of high acoustic resistance over a wide band of acoustic frequencies.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Physics & Mathematics (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Electromagnetism (AREA)
  • General Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Building Environments (AREA)
US534958A 1955-09-19 1955-09-19 Acoustic absorber Expired - Lifetime US2935151A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US534958A US2935151A (en) 1955-09-19 1955-09-19 Acoustic absorber
DK323256AA DK108542C (da) 1955-09-19 1956-09-13 Lydabsorberende perforeret plade.

Applications Claiming Priority (1)

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US534958A US2935151A (en) 1955-09-19 1955-09-19 Acoustic absorber

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3103987A (en) * 1960-08-31 1963-09-17 Koppers Co Inc Acoustical panel construction
US3779338A (en) * 1972-01-27 1973-12-18 Bolt Beranek & Newman Method of reducing sound generation in fluid flow systems embodying foil structures and the like
US5782551A (en) * 1994-11-01 1998-07-21 Capaul; Raymond W. Acoustical lighting fixture
US20040070967A1 (en) * 2002-08-06 2004-04-15 Sheila Kennedy Acoustic light emitting module
US20080029336A1 (en) * 2006-06-10 2008-02-07 Patrick Sigler Acoustic panel
EP2742376A1 (en) * 2011-09-06 2014-06-18 Koninklijke Philips N.V. Light-emitting panel with transparent cellular support panel
EP2788975A4 (en) * 2011-12-09 2015-08-05 3M Innovative Properties Co ACOUSTIC LUMINOUS PANEL
US20150330073A1 (en) * 2012-12-31 2015-11-19 Jean-Marc Scherrer Hermetic and Acoustically Absorbent Assembly for a False Partition
US20170110104A1 (en) * 2015-10-16 2017-04-20 Benjamin A. Carlisle Acoustic system and method
EP3227504A1 (en) * 2014-12-05 2017-10-11 Eleda S.r.l. Sound-absorbing element and system
AT516088A3 (de) * 2014-07-17 2019-01-15 Anton Schnurrer Beleuchtungseinrichtung
USD894429S1 (en) 2018-04-13 2020-08-25 Caimi Brevetti S.P.A. Sound absorbing panel
USD895159S1 (en) 2018-04-13 2020-09-01 Caimi Brevetti S.P.A. Sound absorbing panel
USD895158S1 (en) 2018-04-13 2020-09-01 Caimi Brevetti S.P.A. Sound absorbing panel
US11199321B1 (en) * 2019-12-04 2021-12-14 Finelite Inc. Lighting system with acoustic shroud
US11257474B2 (en) * 2017-10-10 2022-02-22 Auralex Acoustics Acoustic system and method

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1726500A (en) * 1928-12-28 1929-08-27 Burgess Lab Inc C F Sound-deadening construction
US2096233A (en) * 1935-09-07 1937-10-19 Universal Insulation Company Perforated plaster sound-deadening construction
US2159488A (en) * 1935-08-01 1939-05-23 Johns Manville Perforated membrane
US2506951A (en) * 1945-11-05 1950-05-09 Leroy C Doane Foraminous sheet material and luminaire made therefrom
DE866183C (de) * 1951-11-11 1953-02-09 Paul Mueller Blendfreie Abschirmung an Langfeldleuchten, Neonroehren od. dgl.
US2656004A (en) * 1947-04-29 1953-10-20 Rca Corp Multisection acoustic filter
US2659808A (en) * 1949-06-22 1953-11-17 F W Wakefield Brass Company Combination luminous and acoustical ceiling
US2703627A (en) * 1954-04-16 1955-03-08 Pittsburgh Corning Corp Acoustic tile

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1726500A (en) * 1928-12-28 1929-08-27 Burgess Lab Inc C F Sound-deadening construction
US2159488A (en) * 1935-08-01 1939-05-23 Johns Manville Perforated membrane
US2096233A (en) * 1935-09-07 1937-10-19 Universal Insulation Company Perforated plaster sound-deadening construction
US2506951A (en) * 1945-11-05 1950-05-09 Leroy C Doane Foraminous sheet material and luminaire made therefrom
US2656004A (en) * 1947-04-29 1953-10-20 Rca Corp Multisection acoustic filter
US2659808A (en) * 1949-06-22 1953-11-17 F W Wakefield Brass Company Combination luminous and acoustical ceiling
DE866183C (de) * 1951-11-11 1953-02-09 Paul Mueller Blendfreie Abschirmung an Langfeldleuchten, Neonroehren od. dgl.
US2703627A (en) * 1954-04-16 1955-03-08 Pittsburgh Corning Corp Acoustic tile

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3103987A (en) * 1960-08-31 1963-09-17 Koppers Co Inc Acoustical panel construction
US3779338A (en) * 1972-01-27 1973-12-18 Bolt Beranek & Newman Method of reducing sound generation in fluid flow systems embodying foil structures and the like
US5782551A (en) * 1994-11-01 1998-07-21 Capaul; Raymond W. Acoustical lighting fixture
US20040070967A1 (en) * 2002-08-06 2004-04-15 Sheila Kennedy Acoustic light emitting module
US7303305B2 (en) * 2002-08-06 2007-12-04 Kennedy & Violich Architecture, Ltd. Acoustic light emitting module
US20080029336A1 (en) * 2006-06-10 2008-02-07 Patrick Sigler Acoustic panel
EP2742376A1 (en) * 2011-09-06 2014-06-18 Koninklijke Philips N.V. Light-emitting panel with transparent cellular support panel
EP2788975A4 (en) * 2011-12-09 2015-08-05 3M Innovative Properties Co ACOUSTIC LUMINOUS PANEL
US9194124B2 (en) 2011-12-09 2015-11-24 3M Innovative Properties Company Acoustic light panel
US20150330073A1 (en) * 2012-12-31 2015-11-19 Jean-Marc Scherrer Hermetic and Acoustically Absorbent Assembly for a False Partition
US10260231B2 (en) * 2012-12-31 2019-04-16 Jean-Marc Scherrer Hermetic and acoustically absorbent assembly for a false partition
AT516088A3 (de) * 2014-07-17 2019-01-15 Anton Schnurrer Beleuchtungseinrichtung
US20170342721A1 (en) * 2014-12-05 2017-11-30 Eleda S.R.L. Sound-absorbing element and system
EP3227504A1 (en) * 2014-12-05 2017-10-11 Eleda S.r.l. Sound-absorbing element and system
US10508453B2 (en) * 2014-12-05 2019-12-17 Eleda S.R.L. Sound-absorbing element and system
EP3227504B1 (en) * 2014-12-05 2024-03-27 Eleda S.r.l. Sound-absorbing element and system
US10096310B2 (en) * 2015-10-16 2018-10-09 Auralex Acoustics Acoustic system and method
US20170110104A1 (en) * 2015-10-16 2017-04-20 Benjamin A. Carlisle Acoustic system and method
US11955106B2 (en) 2015-10-16 2024-04-09 Auralex Acoustics Inc Acoustic system and method
US11257474B2 (en) * 2017-10-10 2022-02-22 Auralex Acoustics Acoustic system and method
US11830468B2 (en) 2017-10-10 2023-11-28 Auralex Acoustics Inc. Acoustic system and method
USD894429S1 (en) 2018-04-13 2020-08-25 Caimi Brevetti S.P.A. Sound absorbing panel
USD895159S1 (en) 2018-04-13 2020-09-01 Caimi Brevetti S.P.A. Sound absorbing panel
USD895158S1 (en) 2018-04-13 2020-09-01 Caimi Brevetti S.P.A. Sound absorbing panel
US11199321B1 (en) * 2019-12-04 2021-12-14 Finelite Inc. Lighting system with acoustic shroud

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Publication number Publication date
DK108542C (da) 1968-01-02

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