US3177970A - Sound-absorbing panels with tapered holes therethrough - Google Patents

Sound-absorbing panels with tapered holes therethrough Download PDF

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Publication number
US3177970A
US3177970A US103879A US10387961A US3177970A US 3177970 A US3177970 A US 3177970A US 103879 A US103879 A US 103879A US 10387961 A US10387961 A US 10387961A US 3177970 A US3177970 A US 3177970A
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holes
panel
apertures
sound
sound absorbing
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US103879A
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Boschi Antonio
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Societa Applicazioni Gomma Antivibranti SAGA SpA
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Societa Applicazioni Gomma Antivibranti SAGA SpA
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    • 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
    • E04B9/04—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation comprising slabs, panels, sheets or the like
    • E04B9/0478—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation comprising slabs, panels, sheets or the like of the tray type
    • E04B9/0485—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation comprising slabs, panels, sheets or the like of the tray type containing a filling element
    • 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
    • E04B9/001—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation characterised by provisions for heat or sound insulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
    • F16L55/02—Energy absorbers; Noise absorbers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24273—Structurally defined web or sheet [e.g., overall dimension, etc.] including aperture
    • Y10T428/24322—Composite web or sheet

Definitions

  • the present invention refers to sound-absorbing panels, the main eifective component of which comprises a porus layer, of mineral fibers for example, the thickness of which is proportioned so as to obtain a possibly high degree of acoustic absorption.
  • porous layer is often glued to the rear face of a foraminated relatively thin plate, consisting of a sheet of aluminium or other metal, asbestos-cement or plastics, for example.
  • the main object of this invention is to increase in as simple a way as possible, the sound absorbing power of the above panels in the range of low acoustic frequencies.
  • porous layer with flared holes therethrough, the small ends of which open into one at least of the holes in the foraminated plate.
  • each of such apertures in combination with the respective hole in the plate, is able to form a good low-frequency resonator provided that the thickness of the porous layer and the holes therein and the volume of said holes are suitably proportioned.
  • the porous layer thickness should amount at least to one centimetre; however, in practice, it is not convenient to go below about 1.5-2 em, all the more so that layers of small thickness are not suflicient for a satisfactory absorption of high frequencies.
  • FIGURE 1 shows schematically in cross-sectional partview a sound absorbing covering according to an embodiment of this invention.
  • FIGURE 2 is a similar sectional view of a further embodiment and FIGURE 3 is a diagram showing the sound absorbing properties of a panel of the type shown on FIGURE 1.
  • a facing platen made of aluminum stamped sheet in the form of a rectangular shallow tray having a flat'bottom wall 11 and four side walls 12 (only one of which is visible).
  • wall 11 In the wall 11 numerous through holes 14 are bored, in a preferably uniform distribution.
  • a porous layer 15 is placed, consisting of a mat of mineral wool equalling in thickness the height of the side walls 12.
  • the layer 15 is glued to the bottom wall 11 so as to form a unitary group with the tray.
  • plan cross-sectional profile of such apertures has no particular importance: so, for example, the aperture 16 is shown having a frusto-conical shape (that is having a circular plan cross-sectional profile), the small end of which is centered on one of the holes 14.
  • the aperture 17 is substantially elliptical in plan and its small end includes two holes 14.
  • the panel 10, 15 is hung on the ceiling by means of suitable known suspension members, not shown, anchored to the tray 10. In most cases, the panel is not applied in direct contact of the ceiling 18, but it is hung at a distance D which can be determined experimentally.
  • the continuous curve 20 indicates the sound absorbing characteristics of a panel identical to that shown in FIGURE 1, but lacking the apertures 16, 17; it will be seen from the curve that the efficiency of such a panel becomes appreciable for the frequencies higher than 18002000 c./s., While it is insignificant for lower frequencies.
  • the dotted curve 21 refers to a panel according to FIGURE 1, in which 20% of the total number of holes 14 were associated with flared apertures such as 16, 17 in the layer 15; the curve shows a clear improvement in the range 500-3000 c./s., due to the action of the resonators 14, 16 and 14, 17.
  • the porous layer 15 can be obtained by depositing a porous material or fibres on a flat horizontal support having on its upper face a number of pyramidally shaped projections of a form complemental to that of the apertures 16, 17.
  • FIGURE 2 shows the manner in which such apertures can be obtained by punching.
  • the porous layer 15 is formed by a stack of elemental layers 15a, 15b each of which consists of a mat of fibres.
  • straight apertures 16a, 16b respectively are punched having areas which increase from the lowermost layer towards the uppermost one, and the elemental layers are stacked in registry in such a Way that the apertures 16a, 16b result coaxial therebetween to jointly form a flared aperture equivalent to that denoted by 16 on FIGURE 1.
  • a sound absorbing panel comprising a body of sound absorbing material, said body being generally planar and having major opposite sides, a plurality of holes each of which opens through said opposite sides, said holes being defined by radially continuous peripheral walls extending continuously from one to the other of said opposite sides, said holes being progressively larger .35 from said one tosaid other opposite side, and said panel including a facing platen covering said one side of said body, said platen having apertures therethrough smaller than the holes in said body at said one side thereof, said apertures in the platen connecting with the holes in said v body, said panel being arranged for attachment to a sur- 7 face with said other opposite side adjacent to said surface.

Description

A. BOSCHI A ril 13, 1965 SOUND-ABSORBING PANELS WITH TAPERED HOLES THERETHROUGH Fig.1
I -s w United States Patent 3,177,970 SOUND-ABSORBING PANELS WITH TAPERED HOLES THERETHROUGI-I Antonio Boschi, Milan, Italy, assignor to Societa Applicazioni Gomma Antivibranti S.A.G.A. Societa per Azioni, Milan, Italy Filed Apr. '18, 1961, Ser. No. 103,879 Claims priority, application Italy, Jan. 21, 1961, 977/61 3 Claims. (Cl. 181-33) The present invention refers to sound-absorbing panels, the main eifective component of which comprises a porus layer, of mineral fibers for example, the thickness of which is proportioned so as to obtain a possibly high degree of acoustic absorption.
For mechanical support and also aesthetic reasons, the porous layer is often glued to the rear face of a foraminated relatively thin plate, consisting of a sheet of aluminium or other metal, asbestos-cement or plastics, for example.
It is known, however, that the absorbing power of porous or fibrous layers satisfactorily covers acoustic frequencies which are superior to about 2000 c./s., while it is practically insignificant for frequencies lower than 1000 to 1500 c./s.
The main object of this invention is to increase in as simple a way as possible, the sound absorbing power of the above panels in the range of low acoustic frequencies.
The above object is attained by the present invention,
without applying any supplemental component elements,
by providing the porous layer with flared holes therethrough, the small ends of which open into one at least of the holes in the foraminated plate.
It has been found that each of such apertures, in combination with the respective hole in the plate, is able to form a good low-frequency resonator provided that the thickness of the porous layer and the holes therein and the volume of said holes are suitably proportioned. To
. obtain remarkable results, the porous layer thickness should amount at least to one centimetre; however, in practice, it is not convenient to go below about 1.5-2 em, all the more so that layers of small thickness are not suflicient for a satisfactory absorption of high frequencies.
Of course, owing to the variety of the porous materials available in this field, and considering the known differently compacted mats of vegetable or mineral fibres, it is practically impossible to give, in this place, a general rule for the proportioning of the said apertures.
Generally, it is advisable to start, in every specific case, from the general rules valid for Helmholtz classic resonators, and subsequently improve the results through experimental test.
In the appended drawing:
FIGURE 1 shows schematically in cross-sectional partview a sound absorbing covering according to an embodiment of this invention.
FIGURE 2 is a similar sectional view of a further embodiment and FIGURE 3 is a diagram showing the sound absorbing properties of a panel of the type shown on FIGURE 1.
In the drawing, denotes a facing platen made of aluminum stamped sheet in the form of a rectangular shallow tray having a flat'bottom wall 11 and four side walls 12 (only one of which is visible). In the wall 11 numerous through holes 14 are bored, in a preferably uniform distribution. In the tray 10 a porous layer 15 is placed, consisting of a mat of mineral wool equalling in thickness the height of the side walls 12.
The layer 15 is glued to the bottom wall 11 so as to form a unitary group with the tray.
In the layer '15 (FIGURE 1) numerous apertures 16,
17 are provided, flaring towards the free (upper) surface of the layer.
The plan cross-sectional profile of such apertures has no particular importance: so, for example, the aperture 16 is shown having a frusto-conical shape (that is having a circular plan cross-sectional profile), the small end of which is centered on one of the holes 14. On the contrary, the aperture 17 is substantially elliptical in plan and its small end includes two holes 14.
To form a sound absorbing covering, on a ceiling 18 for example, the panel 10, 15 is hung on the ceiling by means of suitable known suspension members, not shown, anchored to the tray 10. In most cases, the panel is not applied in direct contact of the ceiling 18, but it is hung at a distance D which can be determined experimentally.
It has been found that such a distance affects, in a certain degree, the tune of the resonators formed by the apertures 16, 17 with the respective holes 14. More particularly, there is an upper limit for such a distance, which amounts to about the double of the thickness of the porous layer 15, and which, together with the lower limit of zero value (distance D nil), defines the adjustment range of the panel, that is the range in which the response to the low frequencies varies according to the distance D.
Beyond the said upper limit, the response remains constant and depends upon the factors already mentioned in the introductory paragraphs of this description. In FIG- URE 3 the continuous curve 20 indicates the sound absorbing characteristics of a panel identical to that shown in FIGURE 1, but lacking the apertures 16, 17; it will be seen from the curve that the efficiency of such a panel becomes appreciable for the frequencies higher than 18002000 c./s., While it is insignificant for lower frequencies. On the contrary, the dotted curve 21 refers to a panel according to FIGURE 1, in which 20% of the total number of holes 14 were associated with flared apertures such as 16, 17 in the layer 15; the curve shows a clear improvement in the range 500-3000 c./s., due to the action of the resonators 14, 16 and 14, 17. According to FIGURE 1, the porous layer 15 can be obtained by depositing a porous material or fibres on a flat horizontal support having on its upper face a number of pyramidally shaped projections of a form complemental to that of the apertures 16, 17.
The embodiment shown in FIGURE 2 shows the manner in which such apertures can be obtained by punching. In this embodiment, the porous layer 15 is formed by a stack of elemental layers 15a, 15b each of which consists of a mat of fibres. In the elemental layers straight apertures 16a, 16b respectively, are punched having areas which increase from the lowermost layer towards the uppermost one, and the elemental layers are stacked in registry in such a Way that the apertures 16a, 16b result coaxial therebetween to jointly form a flared aperture equivalent to that denoted by 16 on FIGURE 1.
It is to be understood that the invention is not limited to the embodiments shown on the drawing. Actually, it is presumed that a skilled person will be able to carry out the present invention in any circumstance and by using materials which will not necessarily be the same as those indicated hereinbefore.
What I claim is:
l. A sound absorbing panel comprising a body of sound absorbing material, said body being generally planar and having major opposite sides, a plurality of holes each of which opens through said opposite sides, said holes being defined by radially continuous peripheral walls extending continuously from one to the other of said opposite sides, said holes being progressively larger .35 from said one tosaid other opposite side, and said panel including a facing platen covering said one side of said body, said platen having apertures therethrough smaller than the holes in said body at said one side thereof, said apertures in the platen connecting with the holes in said v body, said panel being arranged for attachment to a sur- 7 face with said other opposite side adjacent to said surface.
2. A sound absorbing panel as claimed in claim 1, wherein said holes in said body are evenly tapered from said one to said other opposite side of said body.
3. A sound absorbing panel as claimed in claim 1, wherein said body comprises a pluralityof layers of material, each layer having holes therethrough larger in size than the holes in the next layer towards said platen, the holes in the respective layers being axially aligned.
4- References Qited by the Examiner UNITED STATES PATENTS Pannati 181-33 LEO SMILOW, Primary Examiner.
C. F. KRAFFT, M. SUSSMAN, Exal ainers.

Claims (1)

1. A SOUND ABSORBING PANEL COMPRISING A BODY OF SOUND ABSORBING MATERIAL, SAID BODY BEING GENERALLY PLANAR AND HAVING MAJOR OPPOSITE SIDES, A PLURALITY OF HOLES EACH OF WHICH OPENS THROUGH SAID OPPOSITE SIDES, SAID HOLES BEING DEFINED BY RADIALLY CONTINUOUS PERIPHERAL WALLS EXTENDING CONTINUOUSLY FROM ONE TO THE OTHER OF SAID OPPOSITE SIDES, SAID HOLES BEING PROGRESSIVELY LARGER FROM SAID ONE TO SAID OTHER OPPOSITE SIDE, AND SAID PANEL INCLUDING A FACING PLATEN COVERING SAID ONE SIDE OF SAID BODY, SAID PLATEN HAVING APERTURES THERETHROUGH SMALLER THAN THE HOLES IN SAID BODY AT SAID ONE SIDE THEREOF, SAID APERTURES IN THE PLATEN CONNECTING WITH THE HOLES IN SAID BODY, SAID PANEL BEING ARRANGED FOR ATTACHMENT TO A SURFACE WITH SID OTHER OPPOSITE SIDE ADJACENT TO SAID SURFACE.
US103879A 1961-01-21 1961-04-18 Sound-absorbing panels with tapered holes therethrough Expired - Lifetime US3177970A (en)

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Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3819009A (en) * 1973-02-01 1974-06-25 Gen Electric Duct wall acoustic treatment
US3831710A (en) * 1973-01-24 1974-08-27 Lockheed Aircraft Corp Sound absorbing panel
US3837426A (en) * 1974-01-04 1974-09-24 Junger M Sound absorbing structural block
US3913702A (en) * 1973-06-04 1975-10-21 Lockheed Aircraft Corp Cellular sound absorptive structure
US4069768A (en) * 1975-05-28 1978-01-24 Bridgestone Tire Company Limited Device for controlling a propagation direction of noise
US4135603A (en) * 1976-08-19 1979-01-23 United Technologies Corporation Sound suppressor liners
US4189027A (en) * 1976-08-19 1980-02-19 United Technologies Corporation Sound suppressor liners
WO1980001183A1 (en) * 1978-11-29 1980-06-12 American Seating Co Improved acoustical wall panel
US4390976A (en) * 1981-01-27 1983-06-28 The United States Of America As Represented By The Secretary Of The Navy Acoustic signal conditioning device
US4395215A (en) * 1981-02-02 1983-07-26 The Procter & Gamble Company Film forming structure for uniformly debossing and selectively aperturing a resilient plastic web and method for its construction
US4399526A (en) * 1981-01-27 1983-08-16 The United States Of America As Represented By The Secretary Of The Navy Acoustic baffle for high-pressure service, modular design
US4486372A (en) * 1983-09-30 1984-12-04 Rohr Industries, Inc. Method for fabricating contoured perforated composite laminate structure
US4747991A (en) * 1981-02-02 1988-05-31 The Procter & Gamble Company Method for debossing and selectively aperturing a resilient plastic web
EP1020846A3 (en) * 1999-01-14 2004-12-01 Nichias Corporation Sound absorbing structure
US20050104245A1 (en) * 1998-07-24 2005-05-19 3M.Innovative Properties Company Process of forming a microperforated polymeric film for sound absorption
WO2005056899A1 (en) * 2003-12-05 2005-06-23 Guy Chenel Masking textile three-dimensional web for building temporary ceiling and corresponding method
FR2864567A1 (en) * 2003-12-05 2005-07-01 Guy Chenel Masking web for temporary ceilings, comprises perforated nonwoven containing holes with reinforced edges
EP1703215A1 (en) * 2005-02-22 2006-09-20 Franco Riello Radiating aluminium panel for false ceilings
US20110100748A1 (en) * 2008-04-14 2011-05-05 Mari Nonogi Multilayer sound absorbing sheet
US20110100749A1 (en) * 2008-05-22 2011-05-05 3M Innovative Properties Company Multilayer sound absorbing structure comprising mesh layer
US20110180348A1 (en) * 2008-04-22 2011-07-28 Mari Nonogi Hybrid sound absorbing sheet
WO2011108527A1 (en) * 2010-03-05 2011-09-09 東拓工業株式会社 Duct hose
US20150259903A1 (en) * 2012-10-05 2015-09-17 Dirtt Environmental Solutions, Ltd. Perforated Acoustic Tiles
US9315985B2 (en) 2012-10-05 2016-04-19 Dirtt Environmental Solutions, Ltd. Center-mounted acoustical substrates
US9328504B2 (en) 2012-10-05 2016-05-03 Dirtt Environmental Solutions, Ltd. Divider wall connection systems and methods
USD755614S1 (en) 2013-11-20 2016-05-10 Dirtt Environmental Solutions, Ltd Flex bracket with knuckle
US9546483B2 (en) 2012-10-05 2017-01-17 Dirtt Environmental Solutions, Ltd. Modular walls with seismic-shiftability
WO2017055124A1 (en) * 2015-09-29 2017-04-06 Akustik & Raum Ag Sound-absorbing element

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3421329A1 (en) * 1984-06-08 1985-12-12 Holzwerke H. Wilhelmi Gmbh & Co Kg, 6335 Lahnau Sound-absorbing building panel for ceilings and walls

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US1554180A (en) * 1924-10-10 1925-09-15 Dahlberg & Company Sound-absorbing board for walls and ceilings
US1825770A (en) * 1929-07-03 1931-10-06 Arthur Sitzman Sound absorbing construction
US2014749A (en) * 1933-02-01 1935-09-17 Coast Insulating Company Acoustic tile
US2089492A (en) * 1935-07-06 1937-08-10 American Radiator Co Duct
US2165101A (en) * 1938-01-06 1939-07-04 George E Hudson Acoustic material
US2362859A (en) * 1940-12-31 1944-11-14 Maurice C Rosenblatt Acoustical building element
US2755882A (en) * 1952-04-22 1956-07-24 Maccaferri Mario Acoustic tiles
US2996138A (en) * 1959-07-10 1961-08-15 Robert A D Schwartz Perforated panel construction
US3074339A (en) * 1959-12-24 1963-01-22 Gomma Antivibranti Applic Sound-proofing, ventilating and conditioning

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1554180A (en) * 1924-10-10 1925-09-15 Dahlberg & Company Sound-absorbing board for walls and ceilings
US1825770A (en) * 1929-07-03 1931-10-06 Arthur Sitzman Sound absorbing construction
US2014749A (en) * 1933-02-01 1935-09-17 Coast Insulating Company Acoustic tile
US2089492A (en) * 1935-07-06 1937-08-10 American Radiator Co Duct
US2165101A (en) * 1938-01-06 1939-07-04 George E Hudson Acoustic material
US2362859A (en) * 1940-12-31 1944-11-14 Maurice C Rosenblatt Acoustical building element
US2755882A (en) * 1952-04-22 1956-07-24 Maccaferri Mario Acoustic tiles
US2996138A (en) * 1959-07-10 1961-08-15 Robert A D Schwartz Perforated panel construction
US3074339A (en) * 1959-12-24 1963-01-22 Gomma Antivibranti Applic Sound-proofing, ventilating and conditioning

Cited By (40)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3831710A (en) * 1973-01-24 1974-08-27 Lockheed Aircraft Corp Sound absorbing panel
US3819009A (en) * 1973-02-01 1974-06-25 Gen Electric Duct wall acoustic treatment
US3913702A (en) * 1973-06-04 1975-10-21 Lockheed Aircraft Corp Cellular sound absorptive structure
US3837426A (en) * 1974-01-04 1974-09-24 Junger M Sound absorbing structural block
US4069768A (en) * 1975-05-28 1978-01-24 Bridgestone Tire Company Limited Device for controlling a propagation direction of noise
US4135603A (en) * 1976-08-19 1979-01-23 United Technologies Corporation Sound suppressor liners
US4189027A (en) * 1976-08-19 1980-02-19 United Technologies Corporation Sound suppressor liners
WO1980001183A1 (en) * 1978-11-29 1980-06-12 American Seating Co Improved acoustical wall panel
US4213516A (en) * 1978-11-29 1980-07-22 American Seating Company Acoustical wall panel
US4399526A (en) * 1981-01-27 1983-08-16 The United States Of America As Represented By The Secretary Of The Navy Acoustic baffle for high-pressure service, modular design
US4390976A (en) * 1981-01-27 1983-06-28 The United States Of America As Represented By The Secretary Of The Navy Acoustic signal conditioning device
US4395215A (en) * 1981-02-02 1983-07-26 The Procter & Gamble Company Film forming structure for uniformly debossing and selectively aperturing a resilient plastic web and method for its construction
US4747991A (en) * 1981-02-02 1988-05-31 The Procter & Gamble Company Method for debossing and selectively aperturing a resilient plastic web
US4486372A (en) * 1983-09-30 1984-12-04 Rohr Industries, Inc. Method for fabricating contoured perforated composite laminate structure
US20050104245A1 (en) * 1998-07-24 2005-05-19 3M.Innovative Properties Company Process of forming a microperforated polymeric film for sound absorption
US6977109B1 (en) * 1998-07-24 2005-12-20 3M Innovative Properties Company Microperforated polymeric film for sound absorption and sound absorber using same
US7731878B2 (en) 1998-07-24 2010-06-08 3M Innovative Properties Company Process of forming a microperforated polymeric film for sound absorption
EP1020846A3 (en) * 1999-01-14 2004-12-01 Nichias Corporation Sound absorbing structure
WO2005056899A1 (en) * 2003-12-05 2005-06-23 Guy Chenel Masking textile three-dimensional web for building temporary ceiling and corresponding method
FR2864564A1 (en) * 2003-12-05 2005-07-01 Guy Chenel THREE-DIMENSIONAL TEXTILE TABLECLOTH FOR TEMPORARY CEILINGS
FR2864567A1 (en) * 2003-12-05 2005-07-01 Guy Chenel Masking web for temporary ceilings, comprises perforated nonwoven containing holes with reinforced edges
EP1703215A1 (en) * 2005-02-22 2006-09-20 Franco Riello Radiating aluminium panel for false ceilings
US8469145B2 (en) * 2008-04-14 2013-06-25 3M Innovative Properties Company Multilayer sound absorbing sheet
CN102057421B (en) * 2008-04-14 2014-12-10 3M创新有限公司 Multilayer sound absorbing sheet
US20110100748A1 (en) * 2008-04-14 2011-05-05 Mari Nonogi Multilayer sound absorbing sheet
US20110180348A1 (en) * 2008-04-22 2011-07-28 Mari Nonogi Hybrid sound absorbing sheet
US8371419B2 (en) 2008-04-22 2013-02-12 3M Innovative Properties Company Hybrid sound absorbing sheet
US20110100749A1 (en) * 2008-05-22 2011-05-05 3M Innovative Properties Company Multilayer sound absorbing structure comprising mesh layer
US8573358B2 (en) 2008-05-22 2013-11-05 3M Innovative Properties Company Multilayer sound absorbing structure comprising mesh layer
JP2011185480A (en) * 2010-03-05 2011-09-22 Totaku Industries Inc Duct hose
CN102770719A (en) * 2010-03-05 2012-11-07 东拓工业株式会社 Duct hose
WO2011108527A1 (en) * 2010-03-05 2011-09-09 東拓工業株式会社 Duct hose
CN102770719B (en) * 2010-03-05 2015-08-19 东拓工业株式会社 Duct hose
US20150259903A1 (en) * 2012-10-05 2015-09-17 Dirtt Environmental Solutions, Ltd. Perforated Acoustic Tiles
US9315985B2 (en) 2012-10-05 2016-04-19 Dirtt Environmental Solutions, Ltd. Center-mounted acoustical substrates
US9328504B2 (en) 2012-10-05 2016-05-03 Dirtt Environmental Solutions, Ltd. Divider wall connection systems and methods
US9546483B2 (en) 2012-10-05 2017-01-17 Dirtt Environmental Solutions, Ltd. Modular walls with seismic-shiftability
US9649831B2 (en) * 2012-10-05 2017-05-16 Dirtt Environmental Solutions, Ltd Perforated acoustic tiles
USD755614S1 (en) 2013-11-20 2016-05-10 Dirtt Environmental Solutions, Ltd Flex bracket with knuckle
WO2017055124A1 (en) * 2015-09-29 2017-04-06 Akustik & Raum Ag Sound-absorbing element

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LU41124A1 (en) 1962-03-19
GB942596A (en) 1963-11-27

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