EP0024044B1 - Sound absorber, in particular for anechoic chambers - Google Patents

Sound absorber, in particular for anechoic chambers Download PDF

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Publication number
EP0024044B1
EP0024044B1 EP80104689A EP80104689A EP0024044B1 EP 0024044 B1 EP0024044 B1 EP 0024044B1 EP 80104689 A EP80104689 A EP 80104689A EP 80104689 A EP80104689 A EP 80104689A EP 0024044 B1 EP0024044 B1 EP 0024044B1
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EP
European Patent Office
Prior art keywords
sound
absorber
recess
sound absorber
base surface
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
Application number
EP80104689A
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German (de)
French (fr)
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EP0024044A3 (en
EP0024044A2 (en
Inventor
Robert Birkler
Gerhard Keller
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G&H Montage GmbH
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G&H Montage GmbH
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Filing date
Publication date
Priority claimed from DE2932473A external-priority patent/DE2932473C2/en
Priority claimed from DE19792938186 external-priority patent/DE2938186A1/en
Application filed by G&H Montage GmbH filed Critical G&H Montage GmbH
Priority to AT80104689T priority Critical patent/ATE8542T1/en
Publication of EP0024044A2 publication Critical patent/EP0024044A2/en
Publication of EP0024044A3 publication Critical patent/EP0024044A3/en
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Publication of EP0024044B1 publication Critical patent/EP0024044B1/en
Expired legal-status Critical Current

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    • 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
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84—Sound-absorbing elements
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84—Sound-absorbing elements
    • E04B2001/8414—Sound-absorbing elements with non-planar face, e.g. curved, egg-crate shaped
    • E04B2001/8419—Acoustical cones or the like, e.g. for anechoic chambers
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84—Sound-absorbing elements
    • E04B2001/8457—Solid slabs or blocks
    • E04B2001/8461—Solid slabs or blocks layered

Definitions

  • the invention relates to a sound-absorbing lining, in particular for anechoic rooms, with a plurality of juxtaposed, essentially wedge-shaped sound absorbers made of sound-absorbing material, and a sound absorber therefor according to the preamble of claim 8.
  • anechoic rooms For example, to record directional characteristics of sound sources or to check and calibrate sound transducers or sound measuring devices, examinations are carried out in extremely low-reflection sound measurement rooms, which are referred to as anechoic rooms and allow sound propagation as in the free field without being influenced by reflections. To prevent reflection, such rooms are lined with sound-absorbing materials, which usually have a strongly structured surface structure. For this purpose, wedge-shaped absorber elements are particularly suitable, ie. H. Elements whose cross-section increases towards the room wall.
  • wedge-shaped absorbers are either symmetrical, with their two converging surfaces having the same angle of inclination with the base surface (DE-C-809599) or asymmetrical, with only one wedge surface of the absorber element being inclined, while the other is at right angles with the Base area forms (DE-C-2 502 846).
  • the zigzag shape of the surface which is created when several of these wedge-shaped absorbers are arranged, results in a continuous transition from the air into the sound-absorbing material, since a preferred plane for reflections is no longer available.
  • the lower limit frequency f o is the frequency at which the sound reflection factor r rises above a value of 0.1, that is to say the sound pressure amplitude of the reflected wave corresponds to more than 1/10 of the amplitude of the incident wave.
  • the value of the sound reflection factor r of 0.1 corresponds to a sound absorption level of 99% of the incident sound energy.
  • an improvement in the absorption capacity of wedge-shaped absorbers of this type in the sense of a further lowering of the lower limit frequency f o can be achieved by arranging the sound absorbers at a certain distance from the wall of the room and on their base surface with a reverberant plate that has openings between the base surfaces of the absorber wedges.
  • the acoustic mechanism of action of this air gap between the base surface of the absorber wedges or the reverberant plate there and the reverberant wall of the room is not known in detail. It is conceivable that effects such as are known in so-called Helmholtz resonators occur.
  • the additional interface for sound propagation which is formed by the base surface of the sound absorbers, could also absorb sound energy; however, in the case of DE-C-878 731, the base surface is covered by the reverberant plate with openings between the absorber wedges, so that the plate acts as a reverberant room wall and an air resonator is additionally provided behind it.
  • the invention has for its object to provide a sound-absorbing lining or a sound absorber for this, which allows a further reduction in the lower cut-off frequency without additional material for a given installation depth.
  • the distance between the base surface of the sound absorbers, which is not acoustically sealed according to the invention, and the sound-hard wall of the room leads to a shift in the material distribution of the absorber elements away from the wall of the room, although not for Large gap widths between the base surface and the wall of the room, the lack of material compared to an installation of the base surface on the wall of the room does not lead to any noticeable disadvantages, whereas the material added to the installation of the base surface on the wall of the room due to the gap there at the front of the absorber elements has a considerable damping effect in Range of the lower limit frequency f o unfolds and is acoustically extremely effective.
  • the lower cut-off frequency can be reduced in this way without additional material, but the installation depth of the sound absorber must be increased in any case, i.e. the thickness of the other Inside the room wall adjoining absorption area. This reduces the usable room size.
  • increased use of material is also inevitable if a maximum value of the gap between the base surface of the absorber elements and the room wall is not to be exceeded.
  • the further essential measure of making a recess in the base area of the absorber surprisingly results in a further significant reduction in the lower cut-off frequency without any other additional changes to the absorber elements or their spatial arrangement. If one determines the frequency response or the reflection factor r in accordance with DIN 52 215 in Kundt's pipe, a lower cut-off frequency is obtained for the sound absorber according to the invention, which is significantly lower than the lower cut-off frequency of the same absorber in the same installation position, but which has no recess in its base area . A comparison measurement showed that the cut-off frequency was reduced from 94 Hz to 84 Hz, ie by more than 10%. It is obvious that the recess also leads to a corresponding saving in material and in particular weight.
  • the base surface is in an area of the sound absorber that is not preferably effective with regard to sound absorption in the manner explained in the introduction, especially not at low frequencies, the large wavelength of which in this area results in only relatively low speed amplitudes and thus damping possibilities.
  • this measure would at most have expected a more or less slight, but in any case existing reduction in the total sound absorption and thus also the sound absorption in the range of the lower cut-off frequency, but in no case an improvement in sound absorption especially in the range of the lower cut-off frequency .
  • measurements actually result in a reduction in sound absorption due to the material recess at certain frequencies in the manner to be expected theoretically, but this reduction in sound absorption is not critical in the case of sound absorbers according to the invention, since at higher frequencies the limit value of the sound reflection factor r of 0.1 in one as in the other case, it is safely undercut.
  • a reduction in sound absorption compared to a smooth base surface can also be specifically excluded if necessary, even at certain higher frequencies.
  • the recess according to the invention would then have to be provided on the inner surface of the central web of the U-shape corresponding to the wedge of the generic type, a measure for which both the constructive and the functional aspect from the DD 81 712 no information can be found.
  • the flat wedge shape of the center bar of the U-shape which can also be found in DD 81 712, obviously only serves to increase the rigidity of the panels and is therefore not comparable to generic, slim wedges with a length of 1 m, for example, because the extremely flat wedge shape of these known panels results in no significant increase in installation depth.
  • FR-A-946 235 it is known to form a sound-absorbing element from a base plate with an edge length of around 20 cm in the example, on which a large number of pointed cones with a height of 10 cm, maximum 20 cm, is arranged.
  • the cones can consist of a material which is generally not very effective for sound absorption, for example even of wood.
  • an improvement in sound absorption compared to conventional wedges made of sound-absorbing material is to be achieved, for example according to DE-C-878 731, although the wedges there have a length of, for example, almost 1 m like and usually have an even greater length.
  • the slender, short cones can have rear recesses for receiving an insert body, which in turn can have a cavity and can be designed, for example, as a grid.
  • rear recesses formed in the cones cannot be acoustically effective in the sense of the invention, because the base surface of the cone is in any case placed directly on the associated support plate, so that the recesses on the back of the wooden cones, for example, are sealed .
  • the outline of the recess on the base surface can have the shape of a polygon.
  • the recess preferably has the outline shape of a triangle, rectangle or trapezoid perpendicular to the room wall.
  • Such a rectangular sectional shape can completely penetrate the base surface, which is, for example, a square or a rectangle with a larger surface, so that the recess is open on two opposite sides. This is the case, for example, if a wedge with a rectangular base is cut from the base surface in such a way that a continuous slot results. If a symmetrical wedge is cut into the absorber, there is at the same time a linear increase in the two side surfaces of the recess.
  • a non-linear increase occurs in the case of forms of the recess which taper in a pointed manner, i.e. H. with pyramid or conical design.
  • mixed forms are also conceivable in which the tapering takes place in steps or a combination of wedge and rounded edge is present.
  • the recesses can either be subsequently cut or punched into an already manufactured sound absorber, or can be provided in the sound absorber from the outset by using appropriately designed shapes. It does not matter whether the sound absorbers are provided with a shaft or just a wedge or pyramid shape exhibit.
  • the area of the recess in the base surface of the sound absorber can vary within a wide range, for example all edges of the recess can coincide with the side lines of the base surface.
  • the base area of the recess in the plane of the base area is preferably about half to a quarter of the base area.
  • the depth of the recess which extends from the base surface to the apex of the recess, can also vary within a wide range. For example, it can extend almost to the tip of the sound absorber.
  • the depth of the recess is preferably one third to one eighth of the total lining depth, the total lining depth being understood to mean the total length of the sound absorber, including the distance of the sound absorber from the room wall.
  • the sound absorber itself can consist of the usually open-cell materials, for example plastic-bound mineral fibers or foam plastic.
  • the finished sound absorbers can be impregnated on their surface.
  • the plastic-bound mineral fiber layers can be covered with a fleece or a textile surface protection made of synthetic or natural fibers.
  • a close-knit, but acoustically transparent, knitted sheath, which consists of synthetic fibers, which are at least flame-retardant, is particularly suitable for this.
  • Such a coating also forms a kind of trickle protection for mineral fiber particles. With such a flame-retardant knitted fabric as a covering in combination with sound absorption material based on mineral fibers, all official fire protection regulations can be met.
  • the textile covering cannot be used as a food source by microorganisms, so that no microorganisms can settle on the absorber, which is also sometimes important.
  • Experiments with molds, yeasts, gram-positive and gram-negative bacteria and spore-forming agents have shown that no infection occurs, even in a humid atmosphere.
  • Such an elastic knitted sheath sticks to the rough surface of the mineral fiber material due to static friction, with a certain clawing occurring.
  • absorber elements of greater overall height can be built up from individual mineral fiber layers, which are stabilized in their mutual position by the sheathing and spanned overall.
  • the covering In the area of the base surface of the absorber wedges, the covering is pulled inward by its elastic property, so that its edge comes to lie in the area of the recess and no thickenings such as beads occur due to the material of the covering on the base surface, which would, for example, make attachment more difficult .
  • This is a particular advantage of such a sheathing in the case of sound absorbers according to the invention, but the use of such an elastic tubular sheathing made of knitted material, which in particular in the direction of the stitch row can have considerably greater extensibility than in the direction of the wales, is not limited to the sound absorber elements according to the invention.
  • the sound absorbers provided with the recess according to the invention can be arranged in several rows or meandering for the construction of anechoic rooms. If the row shape is selected, it is expedient to design the base area of the sound absorbers to be square in order to be able to mount the sound absorbers to be arranged in a further row rotated by 90 ° in each case.
  • the sound absorber shown schematically in Fig. 1 has a wedge-shaped upper part 1, which is symmetrical in the present embodiment.
  • a rectangular shaft 2 adjoins the upper part 1 and has a square base surface 3.
  • a wedge-shaped recess 4 is cut symmetrically to the longitudinal axis of the absorber from the base surface 3, so that a continuous slot is formed.
  • the sound absorber shown consists of mineral fiber material, which is produced in layers 7 of limited thickness. Layers 7 of mineral fiber material of this type are stacked in the illustrated manner to form the sound absorber in the example in each case with the same area, wherein if necessary the individual layers 7 can be stitched together, for example by adhesive. A further securing of the positions of the layers 7 in the composite takes place by means of a sheathing 8 illustrated in FIG. 2 in the form of an elastic tube, which is essentially only stretchable in its circumferential direction of the stitch row, which is illustrated in FIG. 2 by arrow 9.
  • the hose-like sheath 8 has very great extensibility and, for example, can be stretched three times or even more than the untensioned state.
  • stretchability can be achieved well with knitwear, in the simplest case the stitch loops lying in the direction of the wales are pulled out to a considerable length in the knitting or knitting machine, so that the stretchability in the direction of the stitch row can be achieved even with simple, smooth goods. that the long stitch loops lying in the direction of the wales are deformed in the direction of the course.
  • the sheathing 8 is of close-meshed design and on a circular rope machine that works with a high number of needles.
  • the sheath 8 consists in the example of synthetic, flame-retardant fibers, which belong to the group of acrylic fibers. In the present case, acrylonitrile-based synthetic fibers were used.
  • the tube forming the sheath 8 can first be prefabricated endlessly on the circular knitting machine, then cut to the desired length and closed at one end, for example, with an overcast chain stitch seam indicated at 10, such as a safety seam or an imitated safety seam, or in another suitable manner.
  • the assembly of the tube thus formed on the sound absorber can be carried out in the simplest case by rolling up the tube after the seam has been applied and rolling it over the body of the sound absorber after it has been attached to the tip 9. In the case of unfavorable forms of the sound absorber, however, this can lead to technical difficulties, since there is strong static friction due to claws between the meshes of the casing 8 and the fibrous surface of the sound absorber.
  • a pipe with a smooth surface can be used in an unspecified manner as an assembly aid, the diameter of which completely circumscribes the outside diameter of the sound absorber and on the outer circumference of which the tube forming the casing 8 can be easily fitted.
  • the hose contracts and thus forms the elastically relatively tight covering 8 on the outer circumference of the sound absorber, where no more relative movements have to occur.
  • the casing 8 is kept slightly longer than the length L of the sound absorber shown in FIG. 2, so that the open end 8a of the casing 8 contracts over the base surface 3 and its edge can be placed in the recess 4.
  • the sound absorber according to the invention which according to FIG. 2 has the length L, is arranged at a distance 5 from a room wall 6 and thus forms a cavity or gap between the room wall 6 and the absorber.
  • the length L together with the distance 5 forms the total lining depth of the sound absorber arrangement according to the invention.
  • FIG. 3 shows the measurement results of a comparison measurement between a known wedge-shaped sound absorber without a recess and the wedge-shaped sound absorber according to the invention.
  • the sound reflection curve A corresponds to the known absorber
  • curve B corresponds to the absorber with the recess according to the invention.
  • an absorber wedge was used, the total length L of which was 850 mm and which was arranged at a distance of 50 mm from the room wall 6.
  • a material made of plastic-bound mineral fibers with a density of 33.7 kg / m 3 was used for both types of absorbers.
  • the comparison measurement shows that the cut-off frequency of the known sound absorber is 94 Hz, while the lower cut-off frequency of the sound absorber according to the invention is 84 Hz.
  • the frequency range that can be used for sound measurements in the anechoic room has been increased by almost 11%. Sound absorbers for anechoic rooms have lower limit frequencies in the range of at most 100 Hz, and should be as low as possible with regard to the

Description

Die Erfindung betrifft eine schallabsorbierende Auskleidung, insbesondere für schalltote Räume, mit einer Mehrzahl nebeneinandergesetzter, im wesentlichen keilförmiger Schallabsorber aus schallabsorbierendem Material, sowie einen Schallabsorber hierfür nach dem Oberbegriff des Anspruchs 8.The invention relates to a sound-absorbing lining, in particular for anechoic rooms, with a plurality of juxtaposed, essentially wedge-shaped sound absorbers made of sound-absorbing material, and a sound absorber therefor according to the preamble of claim 8.

Etwa um Richtcharakteristiken von Schallquellen aufzunehmen oder um Schallwandler oder Schallmeßgeräte zu überprüfen und zu eichen, werden Untersuchungen in extrem reflexionsarmen Schallmeßräumen durchgeführt, die als schalltote Räume bezeichnet werden und eine Schallausbreitung wie im Freifeld ohne Beeinflussung durch Reflexionen zulassen. Zur Verhinderung der Reflexion sind derartige Räume mit schallschluckenden Materialien ausgekleidet, die üblicherweise eine stark gegliederte Oberflächenstruktur aufweisen. Hierfür eignen sich insbesondere keilförmig ausgebildete Absorberelemente, d. h. Elemente, deren Querschnitt in Richtung auf die Raumwand zunimmt. Diese bekannten keilförmigen Absorber sind entweder symmetrisch ausgebildet, wobei ihre beiden konvergierenden Flächen den gleichen Neigungswinkel mit der Basisfläche besitzen (DE-C-809599) oder aber asymmetrisch ausgebildet, wobei nur eine Keilfläche des Absorberelements geneigt verläuft, während die andere einen rechten Winkel mit der Basisfläche bildet (DE-C-2 502 846). Durch die Zickzack-Form der Oberfläche, die bei einer Anordnung mehrerer dieser keilförmigen Absorber entsteht, ergibt sich ein kontinuierlicher Übergang von der Luft in das Schallschluckmaterial, da eine bevorzugte Ebene für Reflexionen nicht mehr vorhanden ist.For example, to record directional characteristics of sound sources or to check and calibrate sound transducers or sound measuring devices, examinations are carried out in extremely low-reflection sound measurement rooms, which are referred to as anechoic rooms and allow sound propagation as in the free field without being influenced by reflections. To prevent reflection, such rooms are lined with sound-absorbing materials, which usually have a strongly structured surface structure. For this purpose, wedge-shaped absorber elements are particularly suitable, ie. H. Elements whose cross-section increases towards the room wall. These known wedge-shaped absorbers are either symmetrical, with their two converging surfaces having the same angle of inclination with the base surface (DE-C-809599) or asymmetrical, with only one wedge surface of the absorber element being inclined, while the other is at right angles with the Base area forms (DE-C-2 502 846). The zigzag shape of the surface, which is created when several of these wedge-shaped absorbers are arranged, results in a continuous transition from the air into the sound-absorbing material, since a preferred plane for reflections is no longer available.

Von besonderer Bedeutung ist dabei die Schallabsorption bei tiefen Frequenzen. In diesem Zusammenhang wird als untere Grenzfrequenz fo diejenige Frequenz bezeichnet, bei der der Schallreflexionsfaktor r über einen Wert von 0,1 hinaus ansteigt, also die Schalldruckamplitude der reflektierten Welle mehr als 1/10 der Amplitude der einfallenden Welle entspricht. Der Wert des Schallreflexionsfaktors r von 0,1 entspricht einem Schallabsorptionsgrad von 99% der auftreffenden Schallenergie. Unterhalb der unteren Grenzfrequenz fo steigt der Schallreflexionsfaktor r über 0,1 an, so daß für tiefere Frequenzen keine ausreichende Schallabsorption mehr erzielt werden kann, während für alle höheren Frequenzen der Schallreflexionsfaktor r meist deutlich unter 0,1 liegt, wenn ein geeignetes poröses Material für die Schallabsorber verwendet wird.Sound absorption at low frequencies is of particular importance. In this context, the lower limit frequency f o is the frequency at which the sound reflection factor r rises above a value of 0.1, that is to say the sound pressure amplitude of the reflected wave corresponds to more than 1/10 of the amplitude of the incident wave. The value of the sound reflection factor r of 0.1 corresponds to a sound absorption level of 99% of the incident sound energy. Below the lower limit frequency f o the sound reflection factor r rises above 0.1, so that sufficient sound absorption can no longer be achieved for lower frequencies, while for all higher frequencies the sound reflection factor r is usually well below 0.1 if a suitable porous material is used for the sound absorber.

Der Grund für das Auftreten einer recht deutlich definierten unteren Grenzfrequenz für eine ausreichende Schallabsorption, unterhalb der ein steiler Abfall der Schallabsorption erfolgt, dürfte darin liegen, daß bei noch tieferen Frequenzen der Schwingungsbauch des Geschwindigkeitsmaximums der einfallenden und an der schallharten Raumwand reflektierten Welle in einem solchen Abstand von der schallharten Raumwand zu liegen kommt, der die Länge der dort montierten Schallabsorber überschreitet. Es hat sich nämlich gezeigt, daß die untere Grenzfrequenz zu tieferen Frequenzen hin problemlos dadurch verschoben werden kann, daß die keilförmigen Schallabsorber eine größere, von der Raumwand abstehende Länge erhalten, wobei die untere Grenzfrequenz etwa diejenige ist, deren Wellenlänge dem vierfachen Wert des Abstandes der Spitze der Absorberelemente von der Raumwand entspricht. Daraus folgt, daß eine für schalltote Räume ausreichende Schallabsorption nur für diejenigen Frequenzen erzielt werden kann, deren Wellenlänge kleiner ist als der vierfache Abstand der Spitze der Absorberelemente von der Raumwand, so daß also das Maß 2/4 noch in dem Absorbermaterial aufweisenden Abstand von der Raumwand zu liegen kommt. Dabei ist das in unmittelbarer Nachbarschaft der Raumwand liegende Absorptionsmaterial relativ weniger wirksam, da die Schallschnelle in der voll reflektierenden Ebene der schallharten Raumwand definitionsgemäß Null ist und erst im Abstand von der schallharten Raumwand endliche und immer größere Werte annimmt, bis das Maximum in einem Abstand von A14 erreicht ist.The reason for the occurrence of a very clearly defined lower limit frequency for sufficient sound absorption, below which there is a steep drop in sound absorption, is likely to be that, at even lower frequencies, the antinode of the maximum velocity of the incident wave and reflected on the reverberant room wall in such a way There is a distance from the reverberant room wall that exceeds the length of the sound absorbers installed there. It has been shown that the lower cut-off frequency can be easily shifted to lower frequencies by giving the wedge-shaped sound absorbers a greater length that protrudes from the wall of the room, the lower cut-off frequency being approximately the one whose wavelength is four times the value of the distance Top of the absorber elements from the room wall corresponds. It follows that a sound absorption sufficient for anechoic rooms can only be achieved for those frequencies whose wavelength is less than four times the distance of the tip of the absorber elements from the wall of the room, so that the dimension 2/4 is still in the absorber material from the Room wall comes to rest. The absorption material in the immediate vicinity of the room wall is relatively less effective, since the speed of sound in the fully reflecting plane of the reverberant room wall is by definition zero and only takes on finite and ever increasing values at a distance from the reverberant wall of the room until the maximum at a distance of A14 is reached.

Eine Verbesserung der Absorptionsfähigkeit von keilförmigen Absorbern dieser Art im Sinne einer weiteren Absenkung der unteren Grenzfrequenz fo kann gemäß der Lehre der DE-C-878 731 dadurch erreicht werden, daß man die Schallabsorber in einem bestimmten Abstand von der Raumwand anordnet und an ihrer Basisfläche mit einer schallharten Platte abdeckt, die zwischen den Basisflächen der Absorberkeile Öffnungen aufweisen. Der akustische Wirkungsmechanismus dieses Luftspaltes zwischen der Basisfläche der Absorberkeile bzw. der dortigen schallharten Platte und der schallharten Raumwand ist nicht im einzelnen bekannt. Es ist denkbar, daß sich hierbei Effekte einstellen, wie sie bei sogenannten Helmholtz-Resonatoren bekannt sind. Dabei könnte die zusätzliche Grenzfläche für die Schallausbreitung, die durch die Basisfläche der Schallabsorber gebildet ist, auch Schallenergie absorbieren; jedoch ist die Basisfläche im Falle der DE-C-878 731 durch die schallharte Platte mit Öffnungen zwischen den Absorberkeilen abgedeckt, so daß die Platte gewissermaßen als schallharte Raumwand wirkt und hinter dieser zusätzlich ein Luftresonator vorgesehen ist.According to the teaching of DE-C-878 731, an improvement in the absorption capacity of wedge-shaped absorbers of this type in the sense of a further lowering of the lower limit frequency f o can be achieved by arranging the sound absorbers at a certain distance from the wall of the room and on their base surface with a reverberant plate that has openings between the base surfaces of the absorber wedges. The acoustic mechanism of action of this air gap between the base surface of the absorber wedges or the reverberant plate there and the reverberant wall of the room is not known in detail. It is conceivable that effects such as are known in so-called Helmholtz resonators occur. The additional interface for sound propagation, which is formed by the base surface of the sound absorbers, could also absorb sound energy; however, in the case of DE-C-878 731, the base surface is covered by the reverberant plate with openings between the absorber wedges, so that the plate acts as a reverberant room wall and an air resonator is additionally provided behind it.

Demgegenüber liegt der Erfindung die Aufgabe zugrunde, eine schallabsorbierende Auskleidung bzw. einen Schallabsorber hierfür zu schaffen, der bei vorgegebener Einbautiefe eine weitere Absenkung der unteren Grenzfrequenz ohne zusätzlichen Materialeinsatz ermöglicht.In contrast, the invention has for its object to provide a sound-absorbing lining or a sound absorber for this, which allows a further reduction in the lower cut-off frequency without additional material for a given installation depth.

Die Lösung dieser Aufgabe erfolgt durch die Kombination der kennzeichnenden Merkmale des Anspruchs 1.This object is achieved by the combination of the characterizing features of claim 1.

Der Abstand zwischen der erfindungsgemäß nicht akustisch dicht abgeschlossenen Basisfläche von in den Abmessungen vorgegebenen Schallabsorbern und der schallharten Raumwand führt zu einer Verlagerung der Materialverteilung der Absorberelemente von der Raumwand weg, wobei für nicht zu große Spaltbreiten zwischen der Basisfläche und der Raumwand das gegenüber einer Anlage der Basisfläche an der Raumwand dort fehlende Material zu keinen merklichen Nachteilen führt, während das gegenüber einer Anlage der Basisfläche an der Raumwand durch den dortigen Spalt an der Vorderseite der Absorberelemente hinzukommende Material erhebliche Dämpfungswirkung im Bereich der unteren Grenzfrequenz fo entfaltet und so akustisch überaus wirksam ist. Neben etwaigen sonstigen Effekten im Sinne einer zusätzlichen Vernichtung von Schallenergie ergibt ein Abstand zwischen der Basisfläche der Absorberelemente und der Raumwand bei sonst gleichen Abmessungen, insbesondere gleicher Keillänge, der Absorberelemente somit den Vorteil einer Absenkung der unteren Grenzfrequenz ohne zusätzlichen Materialeinsatz.The distance between the base surface of the sound absorbers, which is not acoustically sealed according to the invention, and the sound-hard wall of the room leads to a shift in the material distribution of the absorber elements away from the wall of the room, although not for Large gap widths between the base surface and the wall of the room, the lack of material compared to an installation of the base surface on the wall of the room does not lead to any noticeable disadvantages, whereas the material added to the installation of the base surface on the wall of the room due to the gap there at the front of the absorber elements has a considerable damping effect in Range of the lower limit frequency f o unfolds and is acoustically extremely effective. In addition to any other effects in the sense of an additional destruction of sound energy, a distance between the base surface of the absorber elements and the wall of the room with otherwise identical dimensions, in particular the same wedge length, gives the absorber elements the advantage of lowering the lower limit frequency without additional material.

Solange somit der Spalt zwischen der Basisfläche der Absorberelemente und der Raumwand nicht zu groß ausfällt, kann eine Absenkung der unteren Grenzfrequenz auf diese Weise zwar ohne zusätzlichen Materialeinsatz erfolgen, jedoch ist in jedem Falle die Einbautiefe der Schallabsorber zu vergrößern, also die Dicke des an die Innenseite der Raumwand anschließenden Absorptionsbereiches. Dies vermindert die nutzbare Raumgröße. Für eine noch weitergehende Absenkung der unteren Grenzfrequenz ist darüber hinaus auch erhöhter Materialeinsatz unausweichlich, wenn ein Maximalwert des Spaltes zwischen der Basisfläche der Absorberelemente und der Raumwand nicht überschritten werden soll.As long as the gap between the base surface of the absorber elements and the wall of the room is not too large, the lower cut-off frequency can be reduced in this way without additional material, but the installation depth of the sound absorber must be increased in any case, i.e. the thickness of the other Inside the room wall adjoining absorption area. This reduces the usable room size. For a further reduction in the lower limit frequency, increased use of material is also inevitable if a maximum value of the gap between the base surface of the absorber elements and the room wall is not to be exceeded.

Die weitere wesentliche Maßnahme der Anbringung einer Ausnehmung in der Basisfläche des Absorbers ergibt überraschenderweise eine weitere deutliche Absenkung der unteren Grenzfrequenz ohne jegliche sonstige zusätzliche Änderungen an den Absorberelementen oder deren räumlicher Anordnung. Bestimmt man den Frequenzgang bzw. den Reflexionsfaktor r nach DIN 52 215 im Kundtschen Rohr, so erhält man für den erfindungsgemäßen Schallabsorber eine untere Grenzfrequenz, die deutlich kleiner ist als die untere Grenzfrequenz desselben Absorbers in derselben Einbaulage, der in seiner Basisfläche jedoch keine Ausnehmung aufweist. Bei einer durchgeführten Vergleichsmessung ergab sich, daß die Grenzfrequenz von 94 Hz auf 84 Hz, also um mehr als 10%, abgesenkt wurde. Es liegt auf der Hand, daß die Ausnehmung darüber hinaus auch zu einer entsprechenden Material- und insbesondere Gewichtseinsparung führt. Ferner können Schwankungen des Raumgewichts des Absorptionsmaterials der Schallabsorber in der Größenordnung von ± 10% bei gleichbleibender Einbautiefe aufgefangen werden, so daß die für ein Nenn-Raumgewicht ermittelte Grenzfrequenz auch bei Raumgewichtsschwankungen erhalten bleibt, die ohne eine solche Ausnehmung in der Basisfläche stärkere Auswirkungen auf die Grenzfrequenz haben.The further essential measure of making a recess in the base area of the absorber surprisingly results in a further significant reduction in the lower cut-off frequency without any other additional changes to the absorber elements or their spatial arrangement. If one determines the frequency response or the reflection factor r in accordance with DIN 52 215 in Kundt's pipe, a lower cut-off frequency is obtained for the sound absorber according to the invention, which is significantly lower than the lower cut-off frequency of the same absorber in the same installation position, but which has no recess in its base area . A comparison measurement showed that the cut-off frequency was reduced from 94 Hz to 84 Hz, ie by more than 10%. It is obvious that the recess also leads to a corresponding saving in material and in particular weight. Furthermore, fluctuations in the density of the absorption material of the sound absorbers can be absorbed in the order of magnitude of ± 10% with a constant installation depth, so that the cut-off frequency determined for a nominal density is retained even with fluctuations in density, which without such a recess in the base area have a greater impact on the Have cutoff frequency.

Eine wissenschaftliche Klärung dieser Phänomene ist noch nicht gelungen. Die erfindungsgemäß erzielbaren Wirkungen waren auch nicht zu erwarten, da durch die Wegname von Material im Bereich der Basisfläche - abgesehen von der natürlich zu erwartenden Material- und Gewichtseinsparung - im akustischen Bereich an sich nur Nachteile zu erwarten waren. Zwar liegt die Basisfläche in einem Bereich des Schallabsorbers, der hinsichtlich der Schallabsorption in der einleitend erläuterten Weise nicht bevorzugt wirksam ist, insbesondere nicht bei tiefen Frequenzen, deren große Wellenlänge in diesem Bereich nur relativ geringe Geschwindigkeitsamplituden und damit Dämpfungsmöglichkeiten ergibt. Auf alle Fälle wäre aber durch diese Maßnahme allenfalls eine mehr oder weniger geringfügige, in jedem Falle aber vorhandene Verminderung der Gesamtschallabsorption und damit auch der Schallabsorption im Bereich der unteren Grenzfrequenz zu erwarten gewesen, keinesfalls aber eine Verbesserung der Schallabsorption vor allem im Bereich der unteren Grenzfrequenz. Bei höheren Frequenzen ergeben Messungen auch tatsächlich in der theoretisch zu erwartenden Weise eine Verminderung der Schallabsorption infolge der Materialausnehmung bei bestimmten Frequenzen, jedoch ist diese Verminderung der Schallabsorption bei erfindungsgemäßen Schallabsorbern unkritisch, da bei höheren Frequenzen der Grenzwert des Schallreflexionsfaktors r von 0,1 im einen wie im anderen Fall sicher unterschritten wird. Durch empirisch ermittelte spezielle Formgebung der Ausnehmung läßt sich darüber hinaus bei Bedarf auch bei bestimmten höheren Frequenzen eine Verminderung der Schallabsorption gegenüber einer glatten Basisfläche gezielt ausschließen.A scientific clarification of these phenomena has not yet been achieved. The effects which can be achieved according to the invention were also not to be expected, since the path names of material in the area of the base area - apart from the material and weight savings which would naturally be expected - in the acoustic area as such only disadvantages were to be expected. The base surface is in an area of the sound absorber that is not preferably effective with regard to sound absorption in the manner explained in the introduction, especially not at low frequencies, the large wavelength of which in this area results in only relatively low speed amplitudes and thus damping possibilities. In any case, this measure would at most have expected a more or less slight, but in any case existing reduction in the total sound absorption and thus also the sound absorption in the range of the lower cut-off frequency, but in no case an improvement in sound absorption especially in the range of the lower cut-off frequency . At higher frequencies, measurements actually result in a reduction in sound absorption due to the material recess at certain frequencies in the manner to be expected theoretically, but this reduction in sound absorption is not critical in the case of sound absorbers according to the invention, since at higher frequencies the limit value of the sound reflection factor r of 0.1 in one as in the other case, it is safely undercut. Through empirically determined special shaping of the recess, a reduction in sound absorption compared to a smooth base surface can also be specifically excluded if necessary, even at certain higher frequencies.

Zur Erklärung des gefundenen Phänomens scheidet auch eine Analogie zur Wirkungsweise des Abstandes oder Spaltes zwischen der Basisfläche der Schallabsorber und der Raumwand aus; denn im Falle des Vorsehens lediglich eines solchen Spaltes ergibt sich die verbesserte Schallabsorption bei tiefen Frequenzen einfach aus dem Umstand, daß Absorberelemente vorgegebener Keillänge durch den Spalt mit ihren Spitzen einen größeren Abstand von der schallharten Raumwand erhalten und so in der theoretisch erklärbaren und oben erläuterten Weise bei tieferen Frequenzen zunehmend wirksam werden. Würden hingegen bei mit der Basisfläche an der Raumwand anliegenden Absorberelementen ohne sonstige Änderung der Lage zur Bildung eines solchen Spaltes im Bereich der Basisflächen Scheiben herausgeschnitten, ergäben sich hingegen keine besseren Schallabsorptionseigenschaften bei tieferen Frequenzen, sondern es würde in der zu erwartenden Weise lediglich eine, wenn auch sehr geringfügige, Verminderung der Gesamtabsorption dadurch auftreten, daß Material, wenn auch an einer nicht kritischen Stelle, weggefallen ist. Im Unterschied hierzu aber ergibt sich erfindungsgemäß durch die bloße Maßnahme einer Wegnahme von Material durch die Ausnehmung im Bereich der Basisfläche eine deutliche Absenkung der unteren Grenzfrequenz sowie eine stärkere Unabhängigkeit der Schallabsorption von Schwankungen der Raumdichte des Schallabsorptionsmaterials, was somit auf ganz anderen Wirkungsmechanismen beruhen muß. Es ist zu unterstellen, daß durch derartige Ausnehmungen im Bereich der Basisfläche zwar ebenfalls eine geringfügige Absenkung der Gesamt-Schallabsorption durch Wegfall von Schallabsorptionsmaterial auftritt, diese Auswirkung aber insbesondere im Bereich tiefer Frequenzen weit mehr als kompensiert wird durch ein noch undefinierbares Phänomen, weiches letztlich zu einer deutlichen Verbesserung der Schallabsorptionseigenschaften speziell im Bereich tiefer Frequenzen führt.To explain the phenomenon found, an analogy to the mode of action of the distance or gap between the base surface of the sound absorber and the wall of the room is also ruled out; because in the case of the provision of only such a gap, the improved sound absorption at low frequencies results simply from the fact that absorber elements of a predetermined wedge length are given a greater distance from the reverberant wall of the room through the gap with their tips, and thus in the manner which can be explained theoretically and explained above become increasingly effective at lower frequencies. If, on the other hand, discs were cut out with the base surface against the wall of the room without any other change in the position to form such a gap in the area of the base surfaces, on the other hand there would be no better sound absorption properties at lower frequencies, but would only be one in the expected manner if there is also a very slight reduction in the total absorption due to the fact that material has been eliminated, even if at a non-critical point. In contrast to this, however, according to the invention, the mere measure of removing material through the recess in the area of the base surface results in a significant lowering of the lower limit frequency and a greater independence of sound absorption from fluctuations in the spatial density of the sound absorption material, which must therefore be based on completely different mechanisms of action. It can be assumed that Such recesses in the area of the base surface also result in a slight reduction in the total sound absorption due to the absence of sound absorption material, but this effect, in particular in the range of low frequencies, is far more than compensated for by a still indefinable phenomenon, which ultimately leads to a significant improvement in the sound absorption properties leads in the range of lower frequencies.

Aus der DD 81 712 sind zwar zur Wandverkleidung dienende Paneele bekannt, die außer einem optisch ansprechenden Aussehen auch Schallabsorptionseigenschaften besitzen sollen und hierzu auch aus offenzelligen verschäumten Kunststoffen hergestellt sein können, also aus einem Schallabsorptionsmaterial. Diese Paneele besitzen im wesentlichen U-Form und damit an ihrer der Wand benachbarten Seite einen großen Hohlraum, der der Gewichtsersparnis dient und auch akustisch wirksam sein soll, um insbesondere bei tiefen Frequenzen eine Schallabsorption zu erzielen. Offensichtlich ist dabei an einen Effekt wie bei einem Helmholtz-Resonator gedacht, wie er vermutlich auch bei den einleitend erläuterten bekannten Schallabsorberkeilen für schalltote Räume dadurch auftritt, daß zwischen der Basisfläche der Absorberkeile und der Raumwand ein Spalt vorgesehen ist. Jedoch handelt es sich bei diesen bekannten Paneelen für eine generelle Schallabsorption in gebrauchsbedingt schallbelasteten Räumen um eine dekorative Wandverkleidung mit einer gewissen, weder hinsichtlich Absorptionsfrequenzen noch hinsichtlich Schallabsorptionsgrad genau definierten akustischen Wirksamkeit. Die Innenseite des Mittelsteges der U-Form entspricht dabei schalltechnisch im wesentlichen der Basisfläche gattungsgemäßer Absorberkeile, während die seitlichen Schenkel der U-Form lediglich den Abstand zur Wand überbrücken, um dort ein Ankleben der Paneele zu ermöglichen. Um gattungsgemäße Schallabsorberkeile für schalltote Räume zu schaffen, müßte sich an der Außenseite des Mittelsteges der U-Form ein langer schlanker Keil anschließen, mit einer so großen Länge, welche ;'/4 der unteren Grenzfrequenz entspricht. Um diese ohne Verlängerung dieser Keile dann noch weiter absenken zu können, müßte sodann die erfindungsgemäße Ausnehmung an der der Basisfläche gattungsgemäßer Keile entsprechenden Innenfläche des Mittelsteges der U-Form vorgesehen werden, eine Maßnahme, für die sowohl in konstruktiver als auch funktioneller Hinsicht aus der DD 81 712 keinerlei Hinweis zu entnehmen ist. Die flache Keilform des Mittelsteges der U-Form, die ebenfalls der DD 81 712 zu entnehmen ist, dient offensichtlich nur zur Erhöhung der Steifigkeit der Paneele und ist schon deshalb nicht mit gattungsgemäßen, schlanken Keilen mit einer Länge von beispielsweise 1 m vergleichbar, weil die extrem flache Keilform dieser bekannten Paneele keinerlei ins Gewicht fallende Vergrößerung der Einbautiefe ergibt.From the DD 81 712 panels used for wall cladding are known which, in addition to having an optically appealing appearance, should also have sound absorption properties and, for this purpose, can also be produced from open-cell foamed plastics, ie from a sound absorption material. These panels are essentially U-shaped and therefore have a large cavity on their side adjacent to the wall, which serves to save weight and should also be acoustically effective in order to achieve sound absorption, especially at low frequencies. Obviously, an effect such as that of a Helmholtz resonator is thought of, as it presumably also occurs in the known sound absorber wedges for anechoic rooms explained in the introduction in that a gap is provided between the base surface of the absorber wedges and the wall of the room. However, these known panels for general sound absorption in use-related sound-stressed rooms are decorative wall claddings with a certain acoustic effectiveness that is neither precisely defined in terms of absorption frequencies nor in terms of sound absorption. The inside of the central web of the U-shape corresponds in terms of sound technology essentially to the base surface of generic absorber wedges, while the side legs of the U-shape only bridge the distance to the wall in order to allow the panels to be glued there. In order to create generic sound absorber wedges for anechoic rooms, a long, slender wedge would have to be attached to the outside of the center web of the U-shape, with a length which corresponds to the lower limit frequency. In order to be able to lower this even further without extending these wedges, the recess according to the invention would then have to be provided on the inner surface of the central web of the U-shape corresponding to the wedge of the generic type, a measure for which both the constructive and the functional aspect from the DD 81 712 no information can be found. The flat wedge shape of the center bar of the U-shape, which can also be found in DD 81 712, obviously only serves to increase the rigidity of the panels and is therefore not comparable to generic, slim wedges with a length of 1 m, for example, because the extremely flat wedge shape of these known panels results in no significant increase in installation depth.

Aus der FR-A-946 235 ist es bekannt, ein schallabsorbierendes Element aus einer Grundplatte mit im Beispielsfalle rund 20 cm Kantenlänge zu bilden, auf der eine Vielzahl von spitzen Kegeln mit einer Höhe von 10 cm, maximal 20 cm, angeordnet ist. Die Kegel können dabei aus einem zur Schallabsorption gemeinhin wenig wirksamen Material bestehen, beispielsweise sogar aus Holz. Mit einer solchen stachelartigen Anordnung einer Vielzahl schlanker, kurzer Kegel aus ggf. schallhartem Material soll eine Verbesserung der Schallabsorption gegenüber üblichen Keilen aus schallabsorbierendem Material etwa gemäß der DE-C-878 731 erzielt werden, obwohl die dortigen Keile eine Länge von beispielsweise fast 1 m haben mögen und üblicherweise eine noch größere Länge besitzen. Dabei können die schlanken, kurzen Kegel rückwärtige Ausnehmungen zur Aufnahme eines Einsatzkörpers besitzen, der seinerseits wiederum einen Hohlraum aufweisen kann und beispielsweise als Gitter ausgebildet sein kann. Dadurch gebildete rückwärtige Ausnehmungen in den Kegeln können jedoch schon deshalb nicht im Sinne der Erfindung akustisch wirksam sein, weil die Basisfläche der Kegel in jedem Falle unmittelbar auf die zugehörige Stützplatte aufgesetzt ist, so daß die Ausnehmungen an der Rückseite der beispielsweise hölzernen Kegel dicht abgeschlossen sind.From FR-A-946 235 it is known to form a sound-absorbing element from a base plate with an edge length of around 20 cm in the example, on which a large number of pointed cones with a height of 10 cm, maximum 20 cm, is arranged. The cones can consist of a material which is generally not very effective for sound absorption, for example even of wood. With such a spike-like arrangement of a plurality of slender, short cones made of possibly sound-hard material, an improvement in sound absorption compared to conventional wedges made of sound-absorbing material is to be achieved, for example according to DE-C-878 731, although the wedges there have a length of, for example, almost 1 m like and usually have an even greater length. The slender, short cones can have rear recesses for receiving an insert body, which in turn can have a cavity and can be designed, for example, as a grid. However, rear recesses formed in the cones cannot be acoustically effective in the sense of the invention, because the base surface of the cone is in any case placed directly on the associated support plate, so that the recesses on the back of the wooden cones, for example, are sealed .

Für die Ausnehmung in der Basisfläche des Schallabsorbers können verschiedene Querschnittsformen gewählt werden, sofern die im Anspruch 1 angegebene Bedingung erfüllt bleibt, daß der lichte Querschnitt der Ausnehmung zum Inneren des Absorbers hin abnimmt. So kann der Grundriß der Ausnehmung an der Basisfläche beispielsweise die Form eines Vielecks besitzen. Vorzugsweise besitzt die Ausnehmung in einem Längsschnitt des Absorberelementes senkrecht zur Raumwand die Umrißform eines Dreiecks, Rechtecks oder Trapezes.Different cross-sectional shapes can be selected for the recess in the base surface of the sound absorber, provided that the condition specified in claim 1 remains fulfilled that the clear cross-section of the recess decreases towards the interior of the absorber. For example, the outline of the recess on the base surface can have the shape of a polygon. In a longitudinal section of the absorber element, the recess preferably has the outline shape of a triangle, rectangle or trapezoid perpendicular to the room wall.

Eine solche rechteckige Schnittform kann die Basisfläche, die beispielsweise ein Quadrat oder ein Rechteck größerer Fläche ist, vollständig durchsetzen, so daß die Ausnehmung an zwei einander gegenüberliegenden Seiten offen ist. Dies ist beispielsweise der Fall, wenn von der Basisfläche her ein Keil mit rechteckiger Grundfläche derart eingeschnitten wird, daß sich ein durchgehender Schlitz ergibt. Sofern ein symmetrischer Keil in den Absorber eingeschnitten wird, ergibt sich zugleich ein linearer Anstieg der beiden Seitenflächen der Ausnehmung.Such a rectangular sectional shape can completely penetrate the base surface, which is, for example, a square or a rectangle with a larger surface, so that the recess is open on two opposite sides. This is the case, for example, if a wedge with a rectangular base is cut from the base surface in such a way that a continuous slot results. If a symmetrical wedge is cut into the absorber, there is at the same time a linear increase in the two side surfaces of the recess.

Ein nichtlinearer Anstieg ergibt sich bei Formen der Ausnehmung, die sich spitzförmig verjüngen, d. h. bei pyramiden- oder kegelförmiger Gestaltung. Daneben sind noch Mischformen denkbar, bei denen die Verjüngung stufenförmig erfolgt oder eine Kombination von Keil und abgerundeter Kante vorliegt.A non-linear increase occurs in the case of forms of the recess which taper in a pointed manner, i.e. H. with pyramid or conical design. In addition, mixed forms are also conceivable in which the tapering takes place in steps or a combination of wedge and rounded edge is present.

Die Ausnehmungen können entweder nachträglich in einen bereits gefertigten Schallabsorber eingeschnitten oder eingestanzt werden, oder aber durch Verwendung entsprechend ausgebildeter Formen bereits von vorneherein im Schallabsorber vorgesehen sein. Es spielt dabei keine Rolle, ob die Schallabsorber mit einem Schaft versehen sind, oder aber lediglich eine Keil- oder Pyramidenform aufweisen. Die Fläche der Ausnehmung in der Basisfläche des Schallabsorbers kann in einem weiten Bereich variieren, beispielsweise können sämtliche Kanten der Ausnehmung mit den Seitenlinien der Basisfläche zusammenfallen. Vorzugsweise beträgt die Grundfläche der Ausnehmung in der Ebene der Basisfläche etwa die Hälfte bis ein Viertel der Basisfläche.The recesses can either be subsequently cut or punched into an already manufactured sound absorber, or can be provided in the sound absorber from the outset by using appropriately designed shapes. It does not matter whether the sound absorbers are provided with a shaft or just a wedge or pyramid shape exhibit. The area of the recess in the base surface of the sound absorber can vary within a wide range, for example all edges of the recess can coincide with the side lines of the base surface. The base area of the recess in the plane of the base area is preferably about half to a quarter of the base area.

Die Tiefe der Ausnehmung, die von der Basisfläche bis zum Scheitel der Ausnehmung reicht, kann ebenfalls in einem weiten Bereich variieren. Sie kann sich beispielsweise bis fast zur Spitze des Schallabsorbers erstrecken. Vorzugsweise beträgt die Tiefe der Ausnehmung ein Drittel bis ein Achtel der Gesamtauskleidungstiefe, wobei unter Gesamtauskleidungstiefe die Gesamtlänge des Schallabsorbers einschließlich des Abstandes des Schallabsorbers von der Raumwand verstanden wird.The depth of the recess, which extends from the base surface to the apex of the recess, can also vary within a wide range. For example, it can extend almost to the tip of the sound absorber. The depth of the recess is preferably one third to one eighth of the total lining depth, the total lining depth being understood to mean the total length of the sound absorber, including the distance of the sound absorber from the room wall.

Der Schallabsorber selbst kann aus den üblicherweise offenzelligen Materialien bestehen, beispielsweise kunststoffgebundenen Mineralfasern oder Schaumkunststoff. Die fertigen Schallabsorber können an ihrer Oberfläche imprägniert werden. Weiterhin können die kunststoffgebundenen Mineralfaserschichten mit einem Vlies oder einem textilen Oberflächenschutz aus Kunst- oder Naturfasern umhüllt sein. Hierzu eignet sich insbesondere eine engmaschige, jedoch akustisch transparente, gestrickte Umhüllung, die aus synthetischen Fasern besteht, welche zumindest schwerentflammbar sind. Eine solche Umhüllung bildet zugleich eine Art Rieselschutz für Mineralfaserpartikel. Mit einem solchen schwerentflammbaren Gestrick als Umhüllung in Kombination mit Schallabsorptionsmaterial auf der Basis von Mineralfasern lassen sich jegliche behördliche Brandschutzbestimmungen erfüllen. Die textile Umhüllung kann von Mikroorganismen nicht als Nahrungsquelle verwendet werden, so daß sich auf dem Absorber keine Mikroorganismen ansiedeln können, was ebenfalls zuweilen von Bedeutung ist. Versuche mit Schimmelpilzen, Hefen, grampositiven und gramnegativen Bakterien sowie Sporenbildnern haben gezeigt, daß auch in feuchter Atmosphäre keinerlei Befall auftritt. Eine solche elastische gestrickte Umhüllung hält durch Haftreibung an der rauhen Oberfläche des Mineralfasermaterials, wobei eine gewisse Verkrallung auftritt. Durch elastische Vorspannung der Umhüllung können Absorberelemente größerer Bauhöhe aus einzelnen Mineralfaserschichten aufgebaut werden, die durch die Umhüllung in ihrer gegenseitigen Lage stabilisiert und insgesamt umspannt werden. Im Bereich der Basisfläche der Absorberkeile wird die Umhüllung durch ihre elastische Eigenschaft nach innen gezogen, so daß ihr Rand in den Bereich der Ausnehmung zu liegen kommt und keine Verdickungen wie Wülste durch das Material der Umhüllung an der Basisfläche auftreten, welche beispielsweise die Befestigung erschweren würden. Dies ist ein besonderer Vorteil einer solchen Umhüllung bei erfindungsgemäßen Schallabsorbern, jedoch ist die Verwendung einer solchen elastischen schlauchförmigen Umhüllung aus Strickmaterial, welches insbesondere in Maschenreihenrichtung erheblich größere Dehnbarkeit besitzen kann als in Maschenstäbchenrichtung, nicht auf erfindungsgemäße Schallabsorberelemente beschränkt.The sound absorber itself can consist of the usually open-cell materials, for example plastic-bound mineral fibers or foam plastic. The finished sound absorbers can be impregnated on their surface. Furthermore, the plastic-bound mineral fiber layers can be covered with a fleece or a textile surface protection made of synthetic or natural fibers. A close-knit, but acoustically transparent, knitted sheath, which consists of synthetic fibers, which are at least flame-retardant, is particularly suitable for this. Such a coating also forms a kind of trickle protection for mineral fiber particles. With such a flame-retardant knitted fabric as a covering in combination with sound absorption material based on mineral fibers, all official fire protection regulations can be met. The textile covering cannot be used as a food source by microorganisms, so that no microorganisms can settle on the absorber, which is also sometimes important. Experiments with molds, yeasts, gram-positive and gram-negative bacteria and spore-forming agents have shown that no infection occurs, even in a humid atmosphere. Such an elastic knitted sheath sticks to the rough surface of the mineral fiber material due to static friction, with a certain clawing occurring. By means of elastic prestressing of the sheathing, absorber elements of greater overall height can be built up from individual mineral fiber layers, which are stabilized in their mutual position by the sheathing and spanned overall. In the area of the base surface of the absorber wedges, the covering is pulled inward by its elastic property, so that its edge comes to lie in the area of the recess and no thickenings such as beads occur due to the material of the covering on the base surface, which would, for example, make attachment more difficult . This is a particular advantage of such a sheathing in the case of sound absorbers according to the invention, but the use of such an elastic tubular sheathing made of knitted material, which in particular in the direction of the stitch row can have considerably greater extensibility than in the direction of the wales, is not limited to the sound absorber elements according to the invention.

Die mit der erfindungsgemäßen Ausnehmung versehenen Schallabsorber können zum Bau von schalltoten Räumen in mehreren Reihen oder mäanderartig angeordnet werden. Sofern die Reihenform gewählt wird, ist es zweckmäßig, die Basisfläche der Schallabsorber quadratisch auszubilden, um die in einer weiteren Reihe anzuordnenden Schallabsorber um jeweils 90° verdreht montieren zu können.The sound absorbers provided with the recess according to the invention can be arranged in several rows or meandering for the construction of anechoic rooms. If the row shape is selected, it is expedient to design the base area of the sound absorbers to be square in order to be able to mount the sound absorbers to be arranged in a further row rotated by 90 ° in each case.

Die Erfindung wird anhand der Zeichnung und der folgenden Beschreibung näher erläutert. Es zeigt

  • Fig. 1 einen erfindungsgemäßen Schallabsorber in einer räumlichen Ansicht ohne Umhüllung,
  • Fig. 2 eine Draufsicht auf den Schallabsorber gemäß Fig. 1, jedoch mit Umhüllung und in seiner Zuordnung zu einer Raumwand, und
  • Fig. 3 ein Diagramm mit zwei Reflexionskurven, in dem ein bekannter Absorber und ein erfindungsgemäßer Absorber verglichen werden.
The invention is explained in more detail with reference to the drawing and the following description. It shows
  • 1 shows a sound absorber according to the invention in a spatial view without an envelope,
  • Fig. 2 is a plan view of the sound absorber according to FIG. 1, but with a cover and in its assignment to a room wall, and
  • 3 shows a diagram with two reflection curves, in which a known absorber and an absorber according to the invention are compared.

Der in Fig. 1 schematisch dargestellte Schallabsorber besitzt ein keilförmiges Oberteil 1, das in der vorliegenden Ausführungsform symmetrisch ausgebildet ist. An das Oberteil 1 schließt sich ein quaderförmiger Schaft 2 an, der eine quadratische Basisfläche 3 hat. In diesen quaderförmigen Schaft 2 ist von der Basisfläche 3 her eine keilförmige Ausnehmung 4 symmetrisch zur Längsachse des Absorbers eingeschnitten, so daß ein durchgehender Schlitz gebildet ist.The sound absorber shown schematically in Fig. 1 has a wedge-shaped upper part 1, which is symmetrical in the present embodiment. A rectangular shaft 2 adjoins the upper part 1 and has a square base surface 3. In this cuboid shaft 2 a wedge-shaped recess 4 is cut symmetrically to the longitudinal axis of the absorber from the base surface 3, so that a continuous slot is formed.

Der dargestellte Schallabsorber besteht aus Mineralfasermaterial, welches in Lagen 7 begrenzter Dicke hergestellt wird. Derartige Lagen 7 von Mineralfasermaterial sind in der veranschaulichten Weise zur Bildung des Schallabsorbers im Beispielsfalle jeweils flächengleich übereinandergestapelt, wobei im Bedarfsfalle eine Heftung der einzelnen Lagen 7 etwa durch Klebstoff erfolgen kann. Eine weitere Lagesicherung der Lagen 7 im Verbund erfolgt durch eine in Fig. 2 veranschaulichte Umhüllung 8 in Form eines elastischen Schlauches, der im wesentlichen nur in seiner in Umfangsrichtung liegenden Maschenreihenrichtung dehnbar ist, die in Fig. 2 mit Pfeil 9 veranschaulicht ist. In Maschenreihenrichtung gemäß Pfeil 9 jedoch weist die schlauchartige Umhüllung 8 sehr große Dehnbarkeit auf und ist beispielsweise gegenüber dem ungespannten Zustand auf den dreifachen Umfang oder noch mehr dehnbar. Eine solche Dehnbarkeit läßt sich mit Maschenware gut erzielen, wobei im einfachsten Fall die in Maschenstäbchenrichtung liegenden Maschenhenkel in der Strick- oder Wirkmaschine zu erheblicher Länge ausgezogen werden, so daß auch bei einfacher, glatter Ware ohne elastischen Faden die Dehnbarkeit in Maschenreihenrichtung dadurch erzielbar ist, daß die in Maschenstäbchenrichtung liegenden langen Maschenhenkel in Maschenreihenrichtung verformt werden. Die Umhüllung 8 ist aus den einleitend geschilderten Gründen engmaschig ausgebildet und auf einer Rundstrickmaschine hergestellt, die mit einer hohen Nadelzahl arbeitet. Die Umhüllung 8 besteht im Beispielsfalle aus synthetischen, schwerentflammbaren Fasern, die der Gruppe der Acrylfasern angehören. Im vorliegenden Fall wurden Kunstfasern auf Acrylnitrilbasis verwendet.The sound absorber shown consists of mineral fiber material, which is produced in layers 7 of limited thickness. Layers 7 of mineral fiber material of this type are stacked in the illustrated manner to form the sound absorber in the example in each case with the same area, wherein if necessary the individual layers 7 can be stitched together, for example by adhesive. A further securing of the positions of the layers 7 in the composite takes place by means of a sheathing 8 illustrated in FIG. 2 in the form of an elastic tube, which is essentially only stretchable in its circumferential direction of the stitch row, which is illustrated in FIG. 2 by arrow 9. In the direction of the stitches according to arrow 9, however, the hose-like sheath 8 has very great extensibility and, for example, can be stretched three times or even more than the untensioned state. Such stretchability can be achieved well with knitwear, in the simplest case the stitch loops lying in the direction of the wales are pulled out to a considerable length in the knitting or knitting machine, so that the stretchability in the direction of the stitch row can be achieved even with simple, smooth goods. that the long stitch loops lying in the direction of the wales are deformed in the direction of the course. For the reasons described in the introduction, the sheathing 8 is of close-meshed design and on a circular rope machine that works with a high number of needles. The sheath 8 consists in the example of synthetic, flame-retardant fibers, which belong to the group of acrylic fibers. In the present case, acrylonitrile-based synthetic fibers were used.

Die Kunstfasern haben folgende physikalische Eigenschaften:

  • - Reißfestigkeit 1,8-2,2 g/dtex
  • - Bruchdehnung 45-55%
  • - relative Knotenfestigkeit 95%
  • - Kochwasserschrumpf 1-2%
  • - spezifisches Gewicht 1,35 g/cm3
  • - Feuchtigkeitsaufnahme 1-2%
  • - Glasumwandlungspunkt 83-85°C
  • - Lichtechtheit (Blauskala) Note 6

(in jeder Farbtiefe, d. h. kein Vergilben)The synthetic fibers have the following physical properties:
  • - Tear resistance 1.8-2.2 g / dtex
  • - elongation at break 45-55%
  • - relative knot strength 95%
  • - Cooking water shrink 1-2%
  • - specific weight 1.35 g / cm 3
  • - moisture absorption 1-2%
  • - Glass transition point 83-85 ° C
  • - Light fastness (blue scale) grade 6

(in every color depth, ie no yellowing)

Der die Umhüllung 8 bildende Schlauch kann auf der Rundstrickmaschine zunächst endlos vorgefertigt, sodann in die gewünschte Länge geschnitten und an einem Ende beispielsweise mit einer bei 10 angedeuteten Überwendlingskettenstichnaht wie einer Sicherheitsnaht oder einer imitierten Sicherheitsnaht, oder auch auf sonstige geeignete Weise verschlossen werden. Die Montage des so gebildeten Schlauches auf dem Schallabsorber kann im einfachsten Fall dadurch erfolgen, daß der Schlauch nach Anbringung der Naht aufgerollt wird und nach Ansetzen mit der Naht 9 auf die Spitze des Schallabsorbers über dessen Körper abgerollt wird. Bei ungünstigen Formen des Schallabsorbers kann dies jedoch zu handwerklichen Schwierigkeiten führen, da eine starke Haftreibung durch Verkrallen zwischen den Maschen der Umhüllung 8 und der faserigen Oberfläche des Schallabsorbers besteht. In einem solchen Fall kann in nicht näher dargestellter Weise als Montagehilfe ein Rohr mit glatter Oberfläche verwendet werden, dessen Durchmesser den Außendurchmesser des Schallabsorbers vollständig umschreibt und auf dessen Außenumfang der die Umhüllung 8 bildende Schlauch problemlos aufgezogen werden kann. Durch Abziehen dieses Montagehilfsrohres zwischen dem Schallabsorber und dem aufgezogenen Schlauch kontrahiert der Schlauch und bildet so die elastisch relativ straff anliegende Umhüllung 8 am Außenumfang des Schallabsorbers, wo keine Relativbewegungen mehr auftreten müssen. Die Umhüllung 8 ist gegenüber der aus Fig. 2 ersichtlichen Länge L des Schallabsorbers etwas länger gehalten, so daß das offene Ende 8a der Umhüllung 8 sich über der Basisfläche 3 kontrahiert und mit seinem Rand in die Ausnehmung 4 hineingelegt werden kann. Damit ist auch der das rückwärtige Ende des Schallabsorbers bildende und zur Lagerung dienende Teil der Basisfläche 3 von einer flachen Lage der Umhüllung 8 abgedeckt und liegen Materialwülste am Ende der Umhüllung lose in der Ausnehmung 4, so daß sie eine saubere Lagerung des Schallabsorbers an der Basisfläche 3 nicht behindern.The tube forming the sheath 8 can first be prefabricated endlessly on the circular knitting machine, then cut to the desired length and closed at one end, for example, with an overcast chain stitch seam indicated at 10, such as a safety seam or an imitated safety seam, or in another suitable manner. The assembly of the tube thus formed on the sound absorber can be carried out in the simplest case by rolling up the tube after the seam has been applied and rolling it over the body of the sound absorber after it has been attached to the tip 9. In the case of unfavorable forms of the sound absorber, however, this can lead to technical difficulties, since there is strong static friction due to claws between the meshes of the casing 8 and the fibrous surface of the sound absorber. In such a case, a pipe with a smooth surface can be used in an unspecified manner as an assembly aid, the diameter of which completely circumscribes the outside diameter of the sound absorber and on the outer circumference of which the tube forming the casing 8 can be easily fitted. By pulling off this auxiliary assembly pipe between the sound absorber and the drawn-on hose, the hose contracts and thus forms the elastically relatively tight covering 8 on the outer circumference of the sound absorber, where no more relative movements have to occur. The casing 8 is kept slightly longer than the length L of the sound absorber shown in FIG. 2, so that the open end 8a of the casing 8 contracts over the base surface 3 and its edge can be placed in the recess 4. So that the rear end of the sound absorber forming and for storage part of the base surface 3 is covered by a flat layer of the casing 8 and material beads at the end of the casing are loosely in the recess 4, so that they are a clean storage of the sound absorber on the base surface 3 do not hinder.

Der erfindungsgemäße Schallabsorber, der gemäß Fig. 2 die Länge L besitzt, wird in einem Abstand 5 von einer Raumwand 6 angeordnet und bildet damit einen Hohlraum oder Spalt zwischen der Raumwand 6 und dem Absorber.The sound absorber according to the invention, which according to FIG. 2 has the length L, is arranged at a distance 5 from a room wall 6 and thus forms a cavity or gap between the room wall 6 and the absorber.

Die Länge L bildet zusammen mit dem Abstand 5 die Gesamtauskleidungstiefe der erfindungsgemäßen Schallabsorberanordnung.The length L together with the distance 5 forms the total lining depth of the sound absorber arrangement according to the invention.

In dem in Fig. 3 gezeigten Diagramm sind die Meßergebnisse einer Vergleichsmessung zwischen einem bekannten keilförmigen Schallabsorber ohne eine Ausnehmung und dem erfindungsgemäßen keilförmigen Schallabsorber dargestellt. Die Schallreflexionskurve A entspricht dabei dem bekannten Absorber, während die Kurve B dem Absorber mit der erfindungsgemäßen Ausnehmung entspricht. In beiden Fällen wurde ein Absorberkeil eingesetzt, dessen Gesamtlänge L 850 mm betrug und der in einem Abstand von 50 mm von der Raumwand 6 angeordnet war. Für beide Absorberarten wurde ein Material aus kunststoffgebundenen Mineralfasern mit einem Raumgewicht von 33,7 kg/m3 verwendet. Aufgrund der Vergleichsmessung ist ersichtlich, daß die Grenzfrequenz des bekannten Schallabsorbers bei 94 Hz liegt, während die untere Grenzfrequenz des erfindungsgemäßen Schallabsorbers 84 Hz beträgt. Der für Schallmessungen im schalltoten Raum ausnutzbare Frequenzbereich wurde also um fast 11% vergrößert. Schallabsorber für schalltote Räume weisen untere Grenzfrequenzen im Bereich von höchstens 100 Hz auf, und sollten hinsichtlich der unteren Grenzfrequenz so tief wie möglich liegen.3 shows the measurement results of a comparison measurement between a known wedge-shaped sound absorber without a recess and the wedge-shaped sound absorber according to the invention. The sound reflection curve A corresponds to the known absorber, while curve B corresponds to the absorber with the recess according to the invention. In both cases, an absorber wedge was used, the total length L of which was 850 mm and which was arranged at a distance of 50 mm from the room wall 6. A material made of plastic-bound mineral fibers with a density of 33.7 kg / m 3 was used for both types of absorbers. The comparison measurement shows that the cut-off frequency of the known sound absorber is 94 Hz, while the lower cut-off frequency of the sound absorber according to the invention is 84 Hz. The frequency range that can be used for sound measurements in the anechoic room has been increased by almost 11%. Sound absorbers for anechoic rooms have lower limit frequencies in the range of at most 100 Hz, and should be as low as possible with regard to the lower limit frequency.

Claims (12)

1. Sound absorbing cladding, especially for anechoic chambers, having a plurality of adjacent, substantially wedge-shaped sound absorbers of sound absorbing material, characterized in that
a) the base surface (3) of the sound absorber is spaced from the acoustically hard chamber wall,
b) the sound absorber is provided with at least one recess (4) in the region of the base surface (3), the cross-section of which tapers towards the interior of the sound absorber, and
c) the base surface (3) of the sound absorber is not acoustically tightly sealed.
2. Cladding according to claim 1, characterized in that the tapering cross-section of the recess (4) tapers linearly.
3. Cladding according to claim 1 or claim 2, characterized in that the tapering cross-section of the recess (4) has a rectangular form.
4. Cladding according to any of claims 1 to 3, characterized in that the recess is formed as a straight slit over the whole height of the sound absorber.
5. Cladding according to claim 1, characterized in that the tapering cross-section of the recess (4) has a triangular, trapezoidal or circular form.
6. Cladding according to any of claims 1 to 5, characterized in that the opening of the recess (4) into the base surface extends for a half to a quarter of the base area (3) of the absorber.
7. Cladding according to any of claims 1 to 6, characterized in that the depth of the recess (4) amounts to a third to an eighth of the whole depth of the sound absorber mounted with spacing (5) from the reflective wall (6).
8. Sound absorber for a sound absorbing cladding according to at least one of claims 1 to 7, which is formed substantially in a wedge shape, characterized in that in the region of the base surface (3) of the absorber at least one recess (4) is formed, the cross-section of which tapers toward the interior of the absorber and the recess is formed as a straight slit.
9. Sound absorber especially according to claim 8, characterized in that a tightly knitted but acoustically transparent cover (8) is provided as protection for the surface, which comprises synthetic fibres which are, at least to some extent, flame resistant.
10. Sound absorber according to claim 9, characterized in that a sleeve serving as a cover (8) is highly extensible in the circumferential, course-wise direction (arrow 9), preferably to more than three times the circumference in the unstretched condition.
11. Sound absorber according to claim 9 or claim 10, characterized in that the absorber has a rough surface and the cover (8) ist held thereon by snagging thereto.
12. Sound absorber according to any one of claims 8 to 11, characterized in that it is comprised of resin bonded mineral fibres which are preferably prepared as individual layers (7) and the layers (7) stapled together to form the sound absorber.
EP80104689A 1979-08-10 1980-08-08 Sound absorber, in particular for anechoic chambers Expired EP0024044B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80104689T ATE8542T1 (en) 1979-08-10 1980-08-08 SOUND ABSORBERS, ESPECIALLY FOR ANICED ROOMS.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE2932473A DE2932473C2 (en) 1979-08-10 1979-08-10 Sound-absorbing body with a base made of mineral fibers
DE2932473 1979-08-10
DE19792938186 DE2938186A1 (en) 1979-09-21 1979-09-21 Sound absorbing element for acoustic chamber - is tapered block of absorbent layers with rear slot and enclosed by mesh layer
DE2938186 1979-09-21

Publications (3)

Publication Number Publication Date
EP0024044A2 EP0024044A2 (en) 1981-02-18
EP0024044A3 EP0024044A3 (en) 1981-07-15
EP0024044B1 true EP0024044B1 (en) 1984-07-18

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ID=25780462

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80104689A Expired EP0024044B1 (en) 1979-08-10 1980-08-08 Sound absorber, in particular for anechoic chambers

Country Status (4)

Country Link
EP (1) EP0024044B1 (en)
DE (1) DE3068592D1 (en)
DK (1) DK342180A (en)
ES (1) ES494138A0 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0080188A1 (en) * 1981-11-19 1983-06-01 G + H MONTAGE GmbH A body, used especially for sound absorption, e.g. in rooms, in the form of a cylindrical tube made of mineral fibres
DE19861016C2 (en) * 1998-12-17 2001-07-05 Fraunhofer Ges Forschung Structured molded bodies for sound absorption

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5317113A (en) * 1992-07-01 1994-05-31 Industrial Acoustics Company, Inc. Anechoic structural elements and chamber
CN101788330B (en) * 2010-02-26 2011-11-23 南京海克医疗设备有限公司 Absorption target for measuring high-intensity focused ultrasound power
CN102691373A (en) * 2012-06-26 2012-09-26 苏州岸肯电子科技有限公司 Sound absorption wedge unit for anechoic chamber
CN106869349A (en) * 2017-03-03 2017-06-20 上海声望声学科技股份有限公司 Sound insulation module with wedge absorber

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DD81712A (en) *
FR875333A (en) * 1940-09-17 1942-09-16 Improvements to noise-absorbing constructions
BE463958A (en) * 1946-03-20
DE878731C (en) * 1950-07-02 1953-06-05 Werner Genest Ges Fuer Isolier High efficiency sound-absorbing arrangement
DE1265959B (en) * 1959-07-27 1968-04-11 Oliver C Eckel Assembly unit wedge-shaped sound absorbing body
DE1609445A1 (en) * 1967-02-25 1970-04-23 Verner Panton Cladding element
DE2502846C3 (en) * 1975-01-24 1978-05-18 Gruenzweig + Hartmann Und Glasfaser Ag, 6700 Ludwigshafen Absorber for damping sound and electromagnetic waves

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0080188A1 (en) * 1981-11-19 1983-06-01 G + H MONTAGE GmbH A body, used especially for sound absorption, e.g. in rooms, in the form of a cylindrical tube made of mineral fibres
DE19861016C2 (en) * 1998-12-17 2001-07-05 Fraunhofer Ges Forschung Structured molded bodies for sound absorption

Also Published As

Publication number Publication date
EP0024044A3 (en) 1981-07-15
ES8104068A1 (en) 1981-03-16
DE3068592D1 (en) 1984-08-23
EP0024044A2 (en) 1981-02-18
ES494138A0 (en) 1981-03-16
DK342180A (en) 1981-02-11

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