EP0171691A2 - Sound insulation element, constructional element, inset, wall block, finished building fabric, partition wall - Google Patents

Abstract

Sound insulation element, construction element, inset, wall block, finished building fabric, partition wall and their fabrication. <IMAGE>

Description

The sound insulation of components such as walls, ceilings or doors depends, among other things, on their structure-borne sound absorption. So far, there are only a few options for increasing structure-borne sound absorption. One of these is the introduction of loose, unbound material such as sand into cavities in masonry or wall shells. This measure has practical disadvantages, especially when adapting components to specified dimensions on the building. The components must be cut to size, with the sand trickling out. A second possibility for achieving structure-borne noise reduction is in sandwich arrangements, with a resilient layer with high structure-borne noise absorption, e.g. from the two shells absorbing the loads. Rubber or plastic is introduced. However, this arrangement is only possible with thin cover shells made of e.g. Sheet steel highly effective, but not with the thick shells that occur in building acoustics.

• a. Wenn die Resonatoren auf einem Bauteil angebracht werden, schwingen die Beschwerungsstücke in der Nähe der Resonanz wie oben besprochen sehr stark. Sie strahlen dann entsprechend verstärkt in den Raum ab, sodaß insgesamt nur eine gennge Verbesserung der Schalldämmung erreicht wird.
• b. Die hohe Körperschalldämpfung bezieht sich nur auf einen schmalen Frequenzbereich, nämlich den Resonanzbereich, siehe Fig. 2. Dort ist die Dämpfung D in Abhängigkeit von der Frequenz f aufgetragen. Es ist ersichtlich, daß die Dämpfung nur in einem schmalen Frequenzgebiet sehr hoch ist. Im Bauwesen ist jedoch eine Dämpfung in einem breiten Frequenzbereich erforderlich.

Finally, based arrangements for structure-borne sound damping are on the resonator principle known, see Fig. 1, wherein individual weight elements (1.1), for example made of concrete or iron by a resilient and at the same time a body-sound-damping layer ₍₁ .2) from, for example rubber on the part to be damped (1.5) be applied. The structure-borne noise-damping effect of this arrangement is based on the fact that such a structure constitutes a resonator system. In the vicinity of the resonance, the weighting element (1.1) makes greatly increased vibrations (for example 5 to 10 times higher) than the component (1.5), as a result of which the resilient layer ( ₁ .2) is compressed or relieved accordingly. This results in correspondingly increased losses of structure-borne noise in this resilient layer. However, this strong structure-borne noise reduction is offset by the following disadvantages:

• a. When the resonators are mounted on a component, the weighting pieces in the vicinity of the resonance vibrate very strongly, as discussed above. They then radiate correspondingly more intensely into the room, so that overall only a slight improvement in sound insulation is achieved.
• b. The high structure-borne noise attenuation relates only to a narrow frequency range, namely the resonance range, see FIG. 2. The attenuation D is plotted as a function of the frequency f. It can be seen that the attenuation is very high only in a narrow frequency range. In construction, however, attenuation in a wide frequency range is required.

For this reason, resonators of this type have so far not been used successfully in structural engineering for damping structure-borne noise.

2.Erfinduno mass-spring resonators

• a. Die Resonantoren, bestehend aus Beschwerings- oder Masseelementen (3.1) und den Feder- und Dämpfungselementen (3.2), werden nicht auf den Bauteilen, sondern in Hohlräume (3.6) innerhalb der Bauteile angebracht, siehe Fig. 3. Dadurch kann die verstärkte Luftschallabstrahlung durch die Resonatoren in den zu schützenden Raum vermieden werden. Die Schallabstrahlung der Resonatoren im Hohlraum selbst ist unschädlich, weil sie zunächst die Wandschale (3.5) zu Schwingungen an regen muß. Die dabei erzeugten Schwingungen sind jedoch vernachlässigbar klein gegen die vom Geräusch im lauten Raum erzeugten Schwingungen der Wandschale.
• b. Eine über einen breiten Frequenzbereich gleichmäßig sich erstreckende Körperschalldämpfung wird durch mehrere Maßnahmen erreicht

The two disadvantages mentioned can be avoided according to the invention in the following ways:

• a. The resonators, consisting of weighting or mass elements (3.1) and the spring and damping elements (3.2), are not attached to the components, but in cavities (3.6) within the components, see Fig. 3. This allows the increased airborne noise to be emitted the resonators in the space to be protected are avoided. The sound radiation from the resonators in the cavity itself is harmless because it first has to vibrate the wall shell (3.5). However, the vibrations generated are negligibly small compared to the vibrations of the wall shell generated by the noise in the noisy room.
• b. Structure-borne noise damping that extends uniformly over a wide frequency range is achieved by several measures

The different resonators attached to a component are tuned to different resonance frequencies by choosing differently formed insulating layers (more or less soft-spring-like) or different weighting elements, see examples in FIGS. ₄ and 5.

In Fic. 4, the weighting elements (4.1) attached in the cavity (4.6) of the component (4.5) are of different weights, while the suspension elements (4.2) are of identical design. In Fig. 5, conversely, the various weighting elements (5.1) are of equal weight, but the suspension elements (5.2) are of different stiffness due to the different profiling of the bearing surface. Since the resonance frequency of the damping systems depends both on the mass of the weighting elements and on the rigidity of the suspension elements, resonance frequencies of different magnitude are achieved with both measures.

Furthermore, the transverse dimensions (perpendicular to the component extension or surface or the formwork surface) of the weighting elements are selected to be relatively small (10 - 50 mm), so that they not only have a single, strongly developed resonance perpendicular to the component surface, but also some other resonances (pitching vibrations and shear vibrations), which each have different resonance frequencies, so that this also results in a strong broadening of the effective frequency range.

Use of bending vibrators as a resonator

Another improvement according to the invention over the prior art is that not only the previously used "mass-spring resonators" according to FIG. 1 can be used, but also so-called. Bending vibrator (6.7) or (7.7) according to Fi ^g. 6 and 7. They have several resonances due to vibrations perpendicular to their longitudinal extent, the type of vibration is shown in Fig. 6 by dashed lines. The position of the resonance frequencies depends on the length of the bending vibrator (6.7) and its transverse dimensions. In contrast to the arrangement in FIG. 1, the mass and suspension required for a resonator do not consist of two separate elements and materials, but are continuously distributed and consist of the same material. The required structure-borne noise damping lies in the material of the vibrator itself. However, additional damping, for example in the form of a rubber strip, can also be applied to the free end of the resonator, see FIG. 31.

The advantage of such bending vibrators is that they can be easily manufactured, for example by sawing slots, see Fig ^g. 29 to 31. The adjustment of the bending vibrators to different resonance frequencies, which is necessary for structure-borne sound absorption, can be achieved by the different choice of the dimensions of the bending transducers can be easily realized in terms of length and transverse dimensions. In addition, such a bending oscillator has not only one, but several resonances.

Two-part construction of the insulation layer (1.2 in Fig. 1)

Finally, the insulation layer (1.2 of Fig. 1) can be made up of two layers. This is shown in Fig. 8 (the component to be damped is omitted there), the layer (8.3) fulfilling the function of the suspension and the layer (8.4), e.g. a tough elastic adhesive layer, the task of structure-borne noise reduction. Depending on the frequency range to be damped, the person skilled in the art must decide whether he needs one layer material or two layers. If primarily the higher frequencies are to be damped, a single layer, e.g. a thin layer of rubber or bitumen felt. If low frequencies are to be attenuated, a soft-elastic foam layer and the rubber layer mentioned will be arranged one behind the other.

Replacement of the insulation layer by shaping the weight layer

In some cases, it is possible to dispense entirely with the resilient and structure-borne sound-absorbing layer (1.2 in FIG. 1) by, according to FIG. 9, making the weighting element (9.1) arched at the point of connection with the component (9.5). that gravity pushes the weighting elements down against the horizontal component (9.5) (applies to ceilings) or that the necessary low contact pressure is generated with the help of a pre-stressed, soft-spring insulation layer (9.8) (e.g. mineral fiber boards).

As is known, the rounding of the contact surface produces a certain amount of suspension between the weighting element (9.1) and the component (9.5). The stiffness of this suspension is lower, the smaller the radius of this curve. By different sized radii of curvature thus the resonance frequency _'made different so that a structure-borne sound damping can be achieved in a wide frequency region and.

9 also has the advantage of a large damping resistance. It is due to the dry friction between the rounding of the weighting elements (9.1) and the component to be damped (9.5) at the contact point. The insulation layer (1.2) in Fig. _{1 The} required resilient and structure-borne noise damping effect is thus achieved in an ideal way without any noteworthy costs.

3. Embodiments 3.1 Mats to stick on e.g. on the inside of the shells of doooelschaliaen walls. Doors. Beamed ceilings

According to Fig. 10 - component to be damped not shown - are on a both damping and resilient base (10.2) from e.g. Infused rubber or bitumen felt, individual weight pieces (10.1) with the help of a later removable and not shown grid. The weightings consist of e.g. Plaster or concrete. A protective layer (10.9) e.g. from a fabric, shown in dashed lines in Fig. 10, attached to the top of the mat. However, according to Fig. 11 also possible, the weighting pieces (11.1) from e.g. Sheet steel e.g. using punching waste, the damping and resilient pad (11.2) made of e.g. Rubber or a structure-borne sound-absorbing plastic around the weighting pieces (11.1), e.g. is vulcanized. The underside can be profiled, this profiling (11.10) being able to be carried out differently at different points in the mat thus obtained.

Finally, such mats or plates may according to FIG. 12 are also made to 13 characterized in that panels are used, for example, of polystyrene foam (11/12), the (12 ₁ 2) having individual recesses are provided. These depressions are filled with a heavy, preferably castable material or building material, for example with plaster, which creates the individual pieces of weight. The bottom of the depressions can be of different thicknesses. A film (12.4) made of, for example, a tough elastic plastic with a high damping effect is glued to the underside. 13 shows a top view of such a mat or plate.

14 shows the arrangement of the mats according to the invention for improving the sound insulation in a double-shell wall. The mats are attached to the inside of the wall shells (14.5) with the weighting pieces (14.1) and the damping and suspension layer ( ₁ 4.2)

A similar arrangement for improving the sound insulation of wooden beam ceilings is shown in Fig. 15. In doing so, e.g. on the underside of the floor (15.13) directly on the beam Mats or panels according to the invention fastened from chipboard, which have weighting pieces (15.1) and a spring and damping layer (15.2) and a holder (15.14) not shown in FIG. 15.

However, it is also possible according to FIG. 16 to attach these mats or plates to the top of a wooden beam ceiling made of chipboard (16.15) and to lay a floating screed or a floating chipboard covering on them. Although it is known that large-format slabs or stones ( ₁ 50-300 mm) are placed on the wooden beam ceilings to improve sound insulation, the present solution differs from this known solution in that the weighting pieces (16.1) are significantly smaller (20-50 mm) and that they are rounded on their underside to produce a suspension and rest loosely. In principle, the weighting pieces can be placed individually (for example with a mass of 15-20 kg / m ² ). However, they can also be connected, for example glued, to the insulation layer (16.8) attached above them.

3.2 Inlets for wall slats in casting mold

An insert for a sound-absorbing wall mat made of gypsum, for example, is a double-sided cassette-insulated panel, e.g. made of soft-spring polystyrene foam (17.16) according to Fig. 17, the cavities (17.17) of which are covered with a resilient and at the same time structure-borne sound-absorbing layer (17.2). This can also be multi-layered. This layer, for example a film or cardboard, has an opening (17.18) for each cavity. The cassette insulation board is set in a suitable manner in the mold of the wall board to be produced and Cast around the outside according to FIG. 18 with plaster, for example. The gypsum also penetrates into the cavities of the insert, the weight pieces (18.2) and the wall shells (18.5) forming.

In terms of sound, a wall made of such wall building boards looks like a double-walled wall, but it has numerous sound bridges in the form of the fixed edge connections (18.19) of the wall building boards. The harmful effect of these sound bridges is greatly reduced by the high structure-borne sound damping of the weight pieces. However, it is also possible to avoid these sound bridges by omitting the connection (18.19), as shown in Fig. 19. acoustically, the soft, spring-loaded, paneled plate (19.16) separates the two shells over the entire surface and, on the other hand, forms an adequate mechanical connection.

3.3 Strip-shaped inlets for shells of wall panels to be glued

However, it is also possible to use such shells (20.5) of wall building boards e.g. with gas concrete but also e.g. in the case of wood chipboard when assembling the double wall panels according to FIG. 20, by means of a structure or sound-absorbing insert (20.20) which absorbs structure-borne noise and at the same time holds the shells together. This insert consists of a soft, elastic insulating strip (20.21), which in the example shown in FIG. 20 consists of a polystyrene foam with a cavity. However, the insulation strip can also be designed in a different way. Weighting pieces (20.1) with a damping layer (20.2), which are glued to the wall shells (20.5), are applied to the insulation strips of any design. This results in a sufficiently firm and still sufficiently soft-elastic connection between the plate shades, which also has a structure-borne noise-damping effect

3.4 Wavy inlets for shells of wall building boards to be glued

The two tasks of increased structure-borne noise damping of the wall shells and resilient connection of the wall shells can be solved particularly simply in the manner shown in FIG. 21. A known, approximately wave-shaped layer (21.22), for example made of rigid polystyrene foam, connects the two wall shells (2 ₁ .5) in a resilient manner. The structure-borne noise reduction is achieved according to the invention by the weighting pieces (21.1) and a structure-borne noise-damping element such as an adhesive layer (2 ₁ .4), which are attached in the troughs of the connecting layer (2 ₁ .22). The wave-shaped layer (21.22) forms the only resilient layer (21.3) of the resonators.

3.5 Inlays for stones or slabs for single-shell walls

According to the theoretical results available, the sound insulation of sound-absorbing walls depends on the material damping of the wall or its loss factor. Sound insulation can therefore be improved by an insert according to the invention.

22 is an insert for casting a mineral building material such as e.g. Gas concrete or plaster shown It consists of two profiled foils (22.23) made of e.g. Cardboard, plastic or foam, which are connected to each other at the constrictions (22.24), possibly even with openings at this point. The inserts are provided with a structure-borne sound-absorbing and resilient material such as cardboard (22.2) on their outer sides, the inserts having openings (22.18). This insert is introduced into the casting mold when the stones or slabs are poured, the cavities of the insert filling with the material of the wall building materials via the opening according to FIG. 23, as a result of which the weight pieces (23.1) are created. The air located between the two embossed foils (22.23) serves to ensure that the two opposing weight pieces do not interfere with each other in their vibrations.

Instead of two foils (22.23), a single foam layer profiled according to FIG. 17 can also be used.

3.6 Structure-borne noise reduction by letting in wall walls

According to Fig. 24, a solution according to the invention for increasing the structure-borne noise reduction of walls is that the bricks or plates are provided with grooves (24.25) on their vertical end faces, into which a structure-borne noise-damping filling (24.26) can then be introduced when the wall is built up . The groove cavities can, as in Fig. 24 shown. elongated perpendicular to the wall surface but also elongated parallel to the wall surface, see Fig. 27.

The advantage of this solution with grooves is that the stones or slabs need to be changed only slightly. An exemplary embodiment for a finished damping element is shown in a vertical section in Fig. 25. It consists of a box (25.27) provided with cavities, e.g. made of foam, which with weighting elements (25.1) e.g. are filled with plaster or concrete. A tough elastic layer (25.4) is applied on the inner (or outer) walls of the box to dampen structure-borne noise e.g. been sprayed on. The walls of the box act as a resilient layer for the resonators.

FIG. 26 shows the mounting of damping elements in the groove cavity (26.25) between the bricks (26.28), with (26. ₁ ) the weighting element and (26.2) the suspension and damping element.

Finally, Fig. 27 shows an arrangement in which a simple element in which individual pieces of weight with a rounded pressure surface (27.1) are applied to a resilient intermediate layer (27.8) e.g. glued from mineral fiber plates and inserted as a whole into the groove cavity (27.25).

3.7 Edge damping of light, solid walls

It is known that one can improve the airborne sound insulation of single-walled light walls, for example from wall building boards made of, for example, plaster or gas concrete, by introducing a structure-borne sound-absorbing strip, for example made of bitumen felt, at the connection points of the wall to the other components. To improve the damping effect a Weichfedemder strips (28.30) according to the invention shown in FIG. 28 is used, which, for example, consists of kassettiertem foam, the cartridges are filled with a heavy material (28.1), for example with gypsum, and fen with a Dämpfungsstre ⁱ (28.2) closed. This arrangement is placed between the lightweight wall to be improved and the flanking components. The strip of, for example, soft-spring foam also reduces the noise. Longitudinal line from the light wall to the adjacent component (28.31). The edge strip according to the invention thus has two acoustic effects: it reduces the vibrations of the lightweight wall due to its structure-borne noise damping and it reduces the transmission of these vibrations to other components.

3.8 Structure-borne sound absorption of the stones from single-shell walls by means of Bieaeschwinaunos resonators

According to Fig. 29 it is achieved in that the bricks (29.28) (e.g. made of gas concrete), bricks or hollow blocks are provided on one or more of their outer boundary surfaces with slot-like depressions (29.32) such that individual, prismatic, elongated columns ( 29.7) arise. They are designated in Fig. 30 in the top view of the stone surface with (30.7). To increase the material damping, a strip of a tough elastic material (31.33), which may be common to them, can be attached to the free end of the prismatic columns (3 ₁ .7) according to FIG. 31.

• 1 weighting elements
• 2 resilient and at the same time structure-borne sound absorbing layer
• 3 only resilient layer
• 4 only damping layer
• 5 component
• 6 cavity
• 7 bending vibrators
• 8 soft elastic insulation layer
• 9 protective layer
• 10 profiling
• 11 sheets of hard foam
• 12 wells
• 13 floor
• 14 bracket
• 15 chipboards
• 16 foam panels with cassettes on both sides
• 17 cavities in a cassette plate
• ₁ 8 opening
• 19 edge connections of the plasterboard
• 20 strip-shaped insert
• 21 soft spring insulation strips
• 22 wavy insulation layer
• 23 profiled foils
• 24 constrictions
• 25 grooves
• 26 structure-borne sound-absorbing filling
• 27 hard foam box
• 28 bricks
• 29 plaster wall tray or similar
• 30 edge strips
• 31 adjacent component
• 32 slots
• 33 structure-borne sound-absorbing strips made of tough elastic material

Claims (26)

_1st Sound insulation element for a cavity in a component such as a component, a wall, ceiling or door and comprehensive - a small-sized weighting element (1.1) and - a resilient and structure-borne sound-absorbing intermediate element (1.2),
the cavity permitting vibrations of the sound insulation element. 2. Flat or strip-shaped soundproofing element for cavities in components such as components, partitions, ceilings or doors and comprising a flat or strip-shaped resilient and structure-borne sound-absorbing intermediate element (Fig. 3, 10 - ₁ 5), in which several small-sized weighting elements (11.1, 12.1 , 13.1) or on its side, which is not intended for contact with the component, several small-sized weighting elements (3.1, 10.1, 14.1, 15.1) are provided. 3. Soundproofing element according to claim 1 or 2, characterized in that the intermediate element (Fig. 8; 2 ₁ ; 2 ₅ ) comprises a resilient layer (8.3; 21.22; 25.27) and a structure-borne sound-absorbing layer (8.4; 21.4; 25.4), wherein - the weighting element (s) can (can) rest on the resilient layer (8.3) or the structure-borne sound-absorbing layer (2 _{1. 4} ; 25.4) and - (if the intermediate element comprises several weighting elements) the layer (21.4; 25.4) provided for supporting the weighting pieces (21.1; 25.1) can be interrupted between the weighting pieces. _4th Sound insulation element according to claim 2 or 3, characterized aekennzeichnet that the individual weight elements have different masses _{(4. 1).} 5. Sound insulation element according to one of claims 2 to 4, characterized in that the intermediate element (12.11) between heavier weighting elements and that of its sides, which is provided for contact with the component, is thinner than lighter weighting elements (12.1). 6. Soundproofing element according to one of claims 2 to 4, characterized in that the intermediate element is profiled on the side which is provided for contact with the component (5.5), so that the intermediate element on the component (5.5) only can be applied in places, the profile provided for the application of the intermediate element in places being the same or different from the weighting element to the weighting element. 7. Soundproofing element according to one of claims 2 to 6, characterized in that the weighting elements (11.1, 12. ₁ , 13. ₁ ; 25.1) in the intermediate element (1 ₁ .2, 12.11, 13.11; 25.27) are embedded or included. 8. Soundproofing element according to one of claims 2 to 7, characterized by weighting elements with a total mass of 2 to 80, in particular 4 to 50 and preferably 8 to 30 kglm ² component. 9. Sound insulation element according to one of the preceding claims, characterized by one or more re weighting elements made of plaster, concrete or iron. 10. Sound insulation element for a cavity in a component such as a component, a wall, ceiling or door and characterized by - one or more small-sized weighting elements (9 _1; 16.1; 27.1), the rounding to rest on the device have, and (9.5; 27.28; 16:15) - If necessary, one or more soft spring elements (9.8; 16.8; 27.8) for locking on the side facing away from the curve. 1 ₁ . Component (for example for partitions, ceilings or doors), characterized by one or more sound insulation elements according to one of the preceding claims. 12. The component according to claim 11, characterized in that the soundproofing element (s) is arranged on one or more longitudinal sides of the plate-shaped component (14.5; 15.13; 16.15; 21.5) or end faces of the plate-shaped component (24.28; 26.28; 27.28) (are). 13. Strip-shaped soundproofing element for edge damping of solid walls, characterized by a strip-shaped resilient and structure-borne sound-absorbing intermediate element (28.2) for bearing against the end face of a wall building board (28.29) and by a soft-resilient cassette strip (28.30) resting on the intermediate element for bearing against the adjacent component such as a fixed wall (28.31), small-sized weighting elements (28.1) being provided on the intermediate element (28.2) in the cassettes of the strip (28.30) which open towards the intermediate element (28.2). 14.Inlay for a sound-technical, two-shell (structural single or double-shell) wall building board, characterized by two groups of chambers (17.17; 22.17) assigned to the two sheep for receiving small-sized weighting elements (18. ₁ ; 23.1), the 18.5; 23.5) facing chamber walls as an intermediate element (17.2; 22.2) are designed to be resilient and structure-borne noise and each chamber ( ₁ 7.17; 22.17) is provided with an opening (17.18; 22.18) facing the assigned shell (18.5; 23.5). 15. Insert according to claim 14, characterized in that the openings are lateral (not central) openings (17.18; 22.18). 16.Inlay for a sound-technical double-shell (structurally single or double-shell) wall building board, characterized by a soft, springy insulation layer (20.21), which is provided on both sides with small-sized weighting elements (20.1), the insulation layer (20.21) guaranteeing that opposing, by the insulation layer (20.21) separate, vibrating weighting elements (20.1) do not hinder each other and the weighting elements (20.1) on their side facing away from the insulation layer (20.21) are provided with resilient and structure-borne sound-absorbing intermediate elements. 17. Insert according to claim 16, characterized in that the insulating layer (20.21) is provided with one or more cavities. ₁ 8. Insert for a soundproof double-shell (structurally single or double-shell) wall building board, characterized by a resilient wave-shaped layer (21.22), in the troughs of which small-sized weighting elements (2 _{1. 1} ) are applied to structure-borne sound-absorbing intermediate elements (21.4). 19. Wall panel, characterized by an insert according to one of claims 14 to 18. 20. A method for producing a soundproofing element according to claim 7, characterized in that the weighting elements are vulcanized into rubber or poured into plastic 21. A method for producing a wall building board with an insert according to claim 14 or 15, characterized in that the insert is poured with a mineral binder, such as gypsum or gas concrete, and the chambers are filled with the binder. 22. Sound insulation element for cavities in components such as components, partitions, ceilings or doors in the form of a bending vibrator (6.7; 7.7; 29.7, 30.7, 31.7). 23. prefabricated component for, for example, partitions, ceilings or doors, the finished component is provided with one or more grooves (FIGS. 24, 26, 27) on one of its surfaces up to all of its surfaces which are intended for contact with other components, - Which in turn are provided with sound insulation elements according to one of the preceding claims (in particular claims 1 to 10, 18 or 22). 24. Prefabricated component according to claim 23, characterized in that one or more bending vibrators (29.7, 30.7, 31.7) are provided as sound insulation elements, which may have been formed during the casting of the prefabricated component or by sawing. 25. A building panel as claimed in claim 24 ^g ekennzeichnetdurch bending transducer in the form of prismatic elongated columns wherein each groove bending vibrator different resonance can be provided. 26. Partition wall or ceiling made of prefabricated components, - wherein said prefabricated elements are each provided on one of its faces up to its surfaces which abut ⁱ gbauteilen other Fert with grooves such that opposing grooves form a common cavity (26.25, 27.25 (Fig 24, 26, 27). and -that it is prefabricated components according to claim 23 or - That soundproofing elements (Fig. 24, 27) have been introduced or poured into the cavities according to claim 7 or 10.

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