Abstract
A sound insulation device (1) for reducing sound transmission, comprising an arrangement of mechanical resonators (2), which each contain at least one vibrating mass (3) and a spring element (4), wherein the mechanical resonators (2) are each tuned such that each resonator has at least one natural frequency in a relevant frequency range, wherein the arrangement of mechanical resonators (2) is configured such that it generates at least one stop band for the propagation of waves in the relevant frequency range.
Claims
1. A sound insulation device for reducing sound transmission, the sound insulation device comprising: an arrangement of mechanical resonators, which each contain at least one vibrating mass and at least one spring element, wherein the mechanical resonators in the arrangement of mechanical resonators are each tuned such that each resonator has at least one natural frequency in a specified frequency range, and wherein the arrangement of mechanical resonators is configured such that it generates at least one stop band for attenuating propagation of waves in the specified frequency range.
2. The sound insulation device according to claim 1, wherein the arrangement of the mechanical resonators is periodic in distance in at least one dimension.
3. The sound insulation device according to claim 2, wherein a distance of the mechanical resonators from one another is smaller than a half-wavelength of a first frequency.
4. The sound insulation device according to claim 2, wherein the periodic arrangement of the mechanical resonators generates a formation of at least one further stop band for elastic wave propagation around at least one further frequency due to Bragg scattering.
5. The sound insulation device according to claim 1, wherein at least one of the arrangement of mechanical resonators resonators is such or the mechanical resonators in the arrangement of mechanical resonators are formed such that a plurality of stop bands are generated for wave propagation.
6. The sound insulation device according to claim 1, wherein individual mechanical resonators have a slightly different frequency tuning so that the at least one stop band is widened.
7. The sound insulation device according to claim 1, wherein the mechanical resonators in the arrangement of mechanical resonators each additionally comprise a damping element.
8. The sound insulation device according to claim 1, wherein the mechanical resonators in the arrangement of mechanical resonators are configured such that their frequency tuning is unable to be influenced by weather or by an external mechanical action.
9. The sound insulation device according to claim 1, wherein at least one of the mechanical resonators in the arrangement of mechanical resonators is configured as a cup resonator, wherein the cup resonator comprises an elastic membrane as the at least one spring element, which forms an outwardly closed-off cup, and a mass arranged in the outwardly closed-off cup.
10. The sound insulation device according to claim 9, wherein the outwardly closed-off cup and the mass are formed in one part.
11. The sound insulation device according to claim 9, wherein the outwardly closed-off cup and the mass are formed as individual parts and the mass is secured in the outwardly closed-off cup.
12. The sound insulation device according to claim 1, wherein at least one of the mechanical resonators in the arrangement of mechanical resonators is configured with at least one elastomer or at least one metal cushion as the at least one spring element.
13. The sound insulation device according to claim 1 wherein at least one of the mechanical resonators in the arrangement of mechanical resonators is configured with a sheet metal strip as the at least one spring element.
14. The sound insulation device according to claim 1, wherein at least one of the mechanical resonators in the arrangement of mechanical resonators is machined in one part from a surface and is defined by cutouts.
15. The sound insulation device according to claim 1, wherein at least one of the mechanical resonators in the arrangement of mechanical resonators is configured with a pre-stressed steel cable as a spring element, from which the at least one vibrating mass is suspended.
16. The sound insulation device according to claim 1, wherein at least one of the mechanical resonators in the arrangement of mechanical resonators is configured with an absorption material as a spring element, in which the at least one vibrating mass is embedded.
17. The sound insulation device according to any claim 1, wherein the mechanical resonators in the arrangement of mechanical resonators additionally comprise an element for energy conversion.
18. The sound insulation device according to claim 1, wherein the mechanical resonators in the arrangement of mechanical resonators additionally comprise an element for adjusting the at least one natural frequency.
19. A noise barrier comprising at least one sound insulation device, wherein the at least one sound insulation device includes: an arrangement of mechanical resonators, wherein each mechanical resonator in the arrangement of mechanical resonators each contain at least one vibrating mass and at least one spring element, wherein the mechanical resonators in the arrangement of mechanical resonators are each tuned such that each resonator has at least one natural frequency in a specified frequency range, and wherein the arrangement of mechanical resonators is configured such that it generates at least one stop band for a propagation of waves in the specified frequency range.
20. The noise barrier according to claim 19, wherein the at least one sound insulation device is arranged at least in some regions on an outer side of the noise barrier.
21. The noise barrier according to claim 19, wherein the noise barrier has a sandwich structure formed from a plurality of layers, and wherein the at least one sound insulation device is arranged in an inner layer of the sandwich structure.
22. The noise barrier according to claim 19, wherein the noise barrier has a sandwich structure formed from a plurality of layers, and wherein a plurality of sound insulation devices are arranged in different layers of the sandwich structure.
23. The noise barrier according to claim 19, wherein the at least one sound insulation device is arranged in a cutout of the noise barrier.
24. The noise barrier according to claim 19, wherein the noise barrier consists of a transparent medium.
25. The noise barrier according to claim 19, wherein the at least one sound insulation device is produced permanently installed with the noise barrier.
26. A component for reducing sound propagation between two areas, comprising a sound insulation device, wherein the sound insulation device includes: an arrangement of mechanical resonators, wherein each mechanical resonator in the arrangement of mechanical resonators each contain at least one vibrating mass and at least one spring element, wherein the mechanical resonators in the arrangement of mechanical resonators are each tuned such that each resonator has at least one natural frequency in a specified frequency range, and wherein the arrangement of mechanical resonators is configured such that it generates at least one stop band for a propagation of waves in the specified frequency range.
Description
[0045] The above-mentioned and other aspects of the invention will become apparent from the detailed description of the exemplary embodiments given with the aid of the following drawings, in which:
[0046] FIGS. 1a and 1b illustrate the operating principle of a vibroacoustic metamaterial, FIGS. 2a, 2b and 2c illustrate various general embodiments of a noise barrier with vibroacoustic metamaterials, FIG. 3a to 3d illustrate various relevant forms of mechanical resonators,
[0047] FIG. 4a shows two perspective views of a first form of a cup resonator, and
[0048] FIG. 4b shows a cross-section through the cup resonator from FIG. 5a,
[0049] FIG. 5a shows two perspective views of a second form of a cup resonator, and
[0050] FIG. 5b shows a cross-section through the cup resonator from FIG. 6a,
[0051] FIG. 6a shows two perspective views of a third form of a cup resonator, and
[0052] FIG. 6b shows a cross-section through the cup resonator from FIG. 7a,
[0053] FIGS. 7a, 7b and 7c show three different damping options using the example of a cup resonator,
[0054] FIG. 8a shows a cross-section through a mechanical resonator with a spring as a spring element,
[0055] FIG. 8b shows a cross-section through a mechanical resonator with an elastomer as a spring element,
[0056] FIG. 8c shows a perspective view of a mechanical resonator with a metal foam as a spring element,
[0057] FIG. 9a is a perspective view of a mechanical resonator consisting of a sheet metal strip with attached masses, FIG. 9b is a side view of the mechanical resonator consisting of a sheet metal strip with attached masses, FIG. 10a is a plan view of an arrangement of mechanical resonators machined from a metal sheet, and
[0058] FIG. 10b shows a perspective view of the arrangement with an enlargement of a portion,
[0059] FIG. 11 shows a schematic representation of mechanical resonators with a steel cable as a spring element,
[0060] FIG. 12a shows a perspective view of a noise barrier provided with a sound insulation device, and
[0061] FIG. 12b shows a frontal view of the noise barrier,
[0062] FIG. 13 shows a cross-section through a noise barrier in cassette construction with two different sound insulation devices,
[0063] FIG. 14a shows a schematic representation of a multi-layer noise barrier with an internally arranged sound insulation device,
[0064] FIG. 14b shows a schematic representation of a multi-layer noise barrier with an externally arranged sound insulation device,
[0065] FIG. 14c shows a schematic representation of a single-layer noise barrier with a sound insulation device arranged on it,
[0066] FIGS. 15a and 15b show schematic representations of noise barriers that are provided with a sound insulation device in some areas,
[0067] FIG. 16a shows a schematic representation of a noise barrier provided with a sound insulation device on two different areas,
[0068] FIG. 16b shows a schematic representation of a noise barrier comprising a window provided with a noise barrier device, FIG. 17a shows a schematic representation of an embodiment of a curved noise barrier provided with a noise barrier device, and
[0069] FIG. 17b shows a schematic representation of a noise protection enclosure provided with a sound insulation device.
[0070] In the following, the claimed subject matter will be explained in greater detail on the basis of the accompanying drawings. Like reference signs refer to like elements.
[0071] FIGS. 1a and 1b show the general structure and operating principle of vibroacoustic metamaterials in abstract form.
[0072] FIG. 1 shows a vibroacoustic metamaterial based on resonant structures, so-called local resonators. In this context, these are mechanical resonators 2.
[0073] These each comprise a vibrating mass 3 and a spring element 4. The arrangement of mechanical resonators 2 is periodic. If the mechanical resonators 2 all have the same frequency tuning, i.e., they all have at least one common natural frequency, when they are excited at this frequency a stop band is formed around it in the arrangement of mechanical resonators 2 and in the medium coupled to it. The propagation of waves in this frequency range, i.e., in the acoustic range of structure-borne and airborne sound, particularly in the range from 50 Hz to 5000 Hz, is therefore greatly reduced. In this range, the structure may practically not be excited to vibrate. As the mechanical resonators 2 may also have several natural frequencies depending on their embodiment, several stop bands may also form around other frequencies. These stop bands may cover different frequency ranges or overlap to create an enlarged stop band. The individual mechanical resonators 2 may also be embodied with a slightly different frequency tuning. This indeed weakens the vibration reduction in the stop band range, but the stop band is widened. The arrangement shown in FIG. 1a thus represents the most general form of sound insulation device. This sound insulation device 1 is independent of its application and does not have to be mounted on a noise barrier 5, but may also be used in other areas. It is initially only defined by the fact that it comprises an arrangement of mechanical resonators that have the same frequency tuning.
[0074] FIG. 1b shows an additional vibroacoustic metamaterial based on the effect of Bragg scattering. This effect is caused by periodically occurring jumps in the phase velocity of waves in a medium, such as those generated by the periodic arrangement of masses 2. The reflection of the waves at these inhomogeneities results in destructive interference in certain frequency ranges, depending on the distances between the inhomogeneities, so that a stop band is also generated. The distance between the inhomogeneities corresponds to half the wavelength of the frequency of the stop band. This effect is of course also present in more complex arrangements, as shown in FIG. 1a. In the context of the present application, however, Bragg scattering plays a rather subordinate role, since the sound insulation device always comprises an arrangement of mechanical resonators 2. However, the Bragg scattering may be used to form additional stop bands.
[0075] In FIGS. 2a, 2b and 2c, various basic embodiments of a noise barrier 5 with a sound insulation device 1 based on vibroacoustic metamaterials are shown schematically in perspective and in cross-section. FIG. 2a shows a noise barrier 5 with mechanical resonators 2 mounted on it (shown in abstract form). In FIG. 2b, the mechanical resonators 2 are installed in the noise barrier 5. In FIG. 2c, the mechanical resonators 2 are integrated into the noise barrier 5 in that spring elements 4 are machined out of it in some areas, here in the form of a thinning of the wall thickness, and vibrating masses 3 are applied to these. However, the masses 3 could also be formed in one part with the noise barrier 5. The mechanical resonators 2 may be connected to the noise barrier 5 by means of adhesive bonding, screwing or other joining methods.
[0076] Various concepts of mechanical resonators that may be used in a sound insulation device 1 are described below. These may be roughly categorized into four different types, which are shown schematically in FIGS. 3a to 3d. FIG. 3a shows a columnar resonator in which a vibrating mass 3 is mounted on a discrete spring element 4. This shape is easy to realize and theoretically possible without additional mass 3. Coil springs, elastomers or metal cushions and foams, for example, are conceivable as spring elements 3. FIG. 3b shows a bending beam resonator. Here, the majority of the beam is marked as spring element 4 and provided with a mass 3 at the tip. However, these do not have to be discrete components; a continuous beam is also conceivable. For this reason, spring element 4 and vibrating mass 3 are unable to be strictly separated in this configuration. A bending beam resonator may easily be manufactured generatively from a plastic using laser cutting or forming processes from sheet metal. FIG.
[0077] 3c illustrates a membrane resonator. A vibrating mass 3 is mounted on a membrane as a spring element 4. The membrane does not have to be flat, but may take on various shapes. However, the membrane must have elastic properties. The vibrating mass 3 may be glued, screwed or otherwise connected to the membrane, or may also be formed in one part with it. FIG. 3d shows a resonator consisting of a vibrating mass 3 and an elastic medium surrounding it as a spring element 4. In a resonator of this shape, the vibrating masses are practically embedded in the spring element.
[0078] Membrane resonators as shown in FIG. 3c have proven to be particularly advantageous for use in a soundproofing arrangement. These may be manufactured as cup resonators in which the membrane is molded into a cup-shaped spring element 4 in which the vibrating mass is arranged. This shape of the resonator makes it possible to construct the mechanical resonator 2 to be closed off from the outside, so that it is protected from external influences.
[0079] Embodiments of such cup resonators are shown in FIGS. 4a to 6b.
[0080] FIGS. 4a and 4b show a cup resonator in which the vibrating mass 3 and the cup are formed in one part as a spring element 4. FIG. 4a shows two perspective views of the resonator, both from diagonally below and from diagonally above. FIG. 4b shows a cross-section through the resonator along line A-A. As this cup resonator is formed in one part, mass 3 and spring element 4 do not need to be connected by additional means. As is visible, the mass 3 is centered in the cup of the spring element 4. To adjust the natural frequency of the resonator, the membrane thickness, the diameter of the cup and the diameter or mass of the vibrating mass may be varied. The cup resonator may also be provided with concentric waves (not shown) on its outer surface in order to reduce the stiffness of the spring element 3. Die casting or injection molding processes, for example, are suitable for manufacturing such a cup resonator. Steel, zinc, aluminum or other metals and plastics may be used as materials. Zinc is particularly suitable because of its low modulus of elasticity and only slightly lower density compared to steel, which makes it ideal for use as an elastic membrane for the resonator. Zinc also acts as corrosion protection and thus offers additional weather resistance. A one-part cup resonator offers the advantages of a small number of parts and simple assembly with relatively simple large-scale production. The lower collar of the cup resonator allows easy application, for example by gluing or screwing, to a surface such as a noise barrier.
[0081] FIGS. 5a and 5b show a cup resonator in which the cup is formed as a spring element 4 from a sheet metal and the vibrating mass 3 is centered in it and firmly connected to it. FIG. 5a shows two perspective views of the resonator, both from diagonally below and from diagonally above. FIG. 5b shows a cross-section through the resonator along line B-B. As this cup resonator is in two parts, mass 3 and spring element 4 must be connected by additional means. The mass 3 may be glued to the cup, for example, but may also be welded or screwed. To adjust the natural frequency of the resonator, the membrane thickness, the diameter of the cup and the diameter or mass of the vibrating mass may be varied. The cup resonator may also be provided with concentric waves or other embossments (not shown) on its outer surface in order to reduce the stiffness of the spring element 3. For the production of such a cup resonator, for example, a metal sheet may be used, which is formed into a cup in a reshaping process. On the other hand, a material with a significantly higher density, such as steel or lead, may be selected to produce the mass, which opens up more possibilities for frequency tuning. This embodiment of the resonator is easy to manufacture using sheet metal and simple reshaping processes. The lower collar of the cup resonator allows easy application, for example by gluing or screwing, to a surface such as a noise barrier.
[0082] FIGS. 6a and 6b also show a cup resonator, the cup as spring element 4 and the vibrating mass 3 are manufactured as individual parts. In this case, the spring element 4 is realized as a plastic cup in which the mass 3 is secured. FIG. 6a shows two perspective views of the resonator, both from diagonally below and from diagonally above. FIG. 6b shows a cross-section of the resonator along line C-C. The plastic cup is manufactured using an injection molding process. The mass 3 is glued to the cup or is molded around the plastic during the manufacture of the cup and thus permanently bonded to it. To adjust the natural frequency of the resonator, the membrane thickness, the diameter of the cup and the diameter or mass of the vibrating mass may be varied. The cup resonator may also be provided with concentric waves or (not shown) on its outer surface in order to reduce the stiffness of the spring element 3. Various plastics with elastic but durable properties are suitable for the manufacture of such a cup resonator. On the other hand, a material with a significantly higher density, such as steel or lead, may be selected to produce the mass, which opens up more possibilities for frequency tuning. By using an injection molding process, this form of cup resonator may be produced in composites and thus easily mass-produced. The lower collar of the cup resonator allows easy application, for example by gluing or screwing, to a surface such as a noise barrier. Similarly to the plastic cup resonator shown in FIGS. 6a and 6b, a cup resonator may also be formed from a metal foam, in which the membrane of the cup consists of a metal foam.
[0083] FIGS. 7a to 7c illustrate various possibilities for damping a mechanical resonator 2 in a sound insulation device 1 using the example of a cup resonator. However, these damping options may also be applied to other types of mechanical resonators 2. In FIG. 7a, the cavity of the cup is filled with a damping foam 6. In FIG. 7b, a damping element 7 made of an elastomer or silicone is inserted into the resonator. In FIG. 7c, the resonator is damped by the fact that it is connected to its base via elastic bonds 8. In FIG. 7d, a damping element is applied to the membrane of the resonator. This may be a layer of bitumen, for example, which additionally seals the resonator and protects it from corrosion. Depending on the shape of the mechanical resonator 2, other forms of damping are also possible. However, these all have the same effect of influencing the shape of the stop band of the sound insulation device 1. In particular, the stop band is weakened by the damping (loses depth), but also widens, which may be a desirable effect. By using damping elements, the shape of the stop band may therefore be specifically adapted to the respective application. FIGS. 8a, 8b and 8c show the different mechanical resonators 2, each of which may be assigned to the type of column resonator shown in FIG. 3a. FIGS. 8a and 8b are similar in that they each comprise a housing 9 in which a vibrating mass 3 is arranged between two spring elements 4.
[0084] In FIG. 8a, the spring element 4 is configured as a coil spring, in FIG. 8b as an elastomer. However, metal cushions could also be used instead of elastomers. The arrangement with the vibrating mass 3 between two spring elements 4 ensures a uniform pre-stress of these, which also allows the frequency tuning to be adjusted. In FIG. 8c, the spring element 4 is a metal foam. Metal foams have an inherent damping effect and are easy to process on a large scale. In addition, a metal vibrating mass 3 may be molded directly onto the metal foam and thus firmly bonded to it. The mechanical resonator 2 is encapsulated by the housing 9 and protected from external influences. Since these embodiments of the mechanical resonator 2 use standardized and readily available components, they are easy to manufacture and versatile in use.
[0085] FIGS. 9a and 9b show a resonator or an arrangement of resonators based on a sheet metal strip. A sheet metal strip may be understood as a bending beam resonator as shown in FIG. 3b. In the embodiment shown in FIG. 9a, however, it also has the characteristics of a membrane resonator as in FIG. 3c. Because the metal strip is folded several times, it defines a series of spring elements 4, each of which is provided with a vibrating mass 3. The masses 3 may be glued or screwed to the sheet metal strip. In this way, an arrangement of resonators 2 may be created using a sheet metal strip and applied in a composite. If damping is required, this may be achieved by elastically bonding the sheet metal strip to the substrate. A further advantage of this embodiment is that there is a relatively large amount of free space between the individual sheet metal strips in an arrangement of such mechanical resonators 2.
[0086] Another embodiment based on a metal sheet is shown in FIGS. 10a and 10b. Here, an arrangement of mechanical resonators 2 is machined out of the surface of a metal sheet. Laser or water jet cutting or other machining processes may be used to produce such a resonator arrangement. In this way, sound insulation devices 1 with large-area arrangements of mechanical resonators 2 may be manufactured in just one step. As may be seen in the magnification in FIG. 10b, cutouts in the sheet metal define plate-shaped vibrating masses 3 and spring elements 4 in the form of webs, which connect the masses to the remaining surface of the sheet metal. However, vibrating masses 3 and spring elements 4 are unable to be defined discretely, as both parts of the arrangement deform when the resonator 2 is excited to vibrate. Frequency tuning is achieved by selecting the shape and dimensions of the vibrating masses 3 and spring elements 4. Due to the relatively low mass of the individual resonators 2, a relatively large surface area is required in this version of a sound insulation device 1, resulting in a low free area ratio. However, this type of resonator may also be made very thin and may therefore be easily integrated into other components, such as noise barriers 5 in cassette construction. To protect against external influences, this form of sound insulation device 1 should be encapsulated as a whole. In addition, the entire metal sheet must be supported over its edges in such a way that the individual mechanical resonators 2 are capable of vibrating. This embodiment has been described here using the example of a metal sheet. However, it may also be realized in other surfaces and materials in which two-dimensional resonators may be defined by cutouts.
[0087] FIG. 11 shows a further embodiment in which a mechanical resonator 2 may be easily extended to form an arrangement of resonators 2. The spring element 4 here is a steel cable that is tensioned between support elements 9 and from which a vibrating mass 3 is suspended. The steel cable may thus serve as a spring element 4 for several resonator unit cells. The frequency tuning may be adjusted by the masses 3 and the pre-stress of the steel cable. The steel cable already provides inherent damping due to internal friction. A two-dimensional arrangement of mechanical resonators 2 may be easily achieved by using several steel cables arranged in parallel. This form of sound insulation device also offers a good free area ratio.
[0088] FIGS. 12a and 12b show an overview of a simple noise barrier 5 provided with a sound insulation device 1. The mechanical resonators 2, which are distributed over the surface of the noise barrier 5, may be, for example, cup resonators, as in FIG. 4a to FIG. 6b, or column resonators, as in FIGS. 8a to 8c. Since the sound insulation device 1 forms a stop band for sound propagation in a relevant area in the noise barrier 5, this reduces sound transmission and may be less massive than conventional noise barriers or have a higher sound transmission reduction. It may also consist of glass or another transparent material. Even with the sound insulation device 1 fitted, the noise barrier is then at least partially transparent and restricts lines of sight to a lesser extent.
[0089] FIG. 13 shows a cross-section through a noise barrier 5 in the cassette construction used in many conventional noise barriers. In this embodiment, however, the noise barrier 5 uses a combination of two sound insulation devices 1 that utilize the properties of vibroacoustic metamaterials. A sound insulation device 1 is arranged on the left-hand side of the noise barrier 5 and uses a sheet metal resonator as shown in FIGS. 10a and b. This is shown in cross-section in the enlargement at the bottom left. To allow the mechanical resonators 2 to vibrate freely, a sound insulation device is mounted on a support element 9. In addition, the sound insulation device 1 is protected from the weather and external mechanical influences by the cassette 10. On the right-hand side, the noise barrier is provided with a second sound insulation device 1. This consists of a matrix of absorption material as a spring element 4, in which mass balls 3 are embedded. This embodiment of the sound insulation device 1 utilizes mechanical resonators 2, as shown in FIG. 3d. As cassette noise barriers are usually already equipped with corresponding cavities for absorption material, the shape of the sound insulation device may be easily combined with this form of noise barrier 5. Similarly, a noise barrier in cassette construction may of course only be realized with a first sound insulation device and the second sound insulation device may be replaced by a conventional absorption material. When using two sound insulation devices 1 on opposite sides of the noise barrier 5, for example, these may be adjusted so that they reduce both the reflection of sound on the side of the noise barrier 5 facing the noise source and the transmission through the noise barrier 5 on the opposite side particularly well.
[0090] Some other forms of noise barriers 5 provided with sound insulation devices 1 are also described below.
[0091] FIG. 14a shows a noise barrier 5 in sandwich construction, which consists of two support panels 11, between which a sound insulation device 1 is arranged. As the sound insulation device 1 increases the sound absorption within the noise barrier due to its stop band, the carrier panels 11 may be thinner and lighter than the components of conventional noise barriers, or may also be made of a material with poorer sound-damping properties, such as glass. Instead, or in addition to this, the sound insulation device may also be attached to the outside of a carrier plate 11, as shown in FIG. 14b. This is particularly useful if the sound insulation device 1 is configured to reduce the transmission or reflection of sound in or from a specific direction. In order to enable a lightweight construction, a noise barrier 5, as shown in FIG. 14c, may also consist of a single carrier plate 11 to which a sound insulation device 1 is attached. In particular, the sound insulation device 1 may also be integrated into the carrier plate or manufactured together with it. A sound insulation device such as those shown in FIGS. 9a and 9b or FIGS. 10a and 10b is suitable for such a noise barrier.
[0092] A noise barrier 5 may also only be provided with a sound insulation device 1 in certain areas. For example, FIG. 15a shows a noise barrier 5 that has a solid lower portion and a thinner upper portion. However, to improve the absorption properties of the upper area, it is provided with a sound insulation device. It is also possible, as indicated in FIG. 15b, to provide an area of the noise barrier 5 with a sound insulation device 1 that is tuned to a frequency range in which this area of the noise barrier 5 is not suitable for reducing sound propagation due to its form, wall thickness or material.
[0093] FIG. 16a shows a noise barrier 5 equipped with two sound insulation devices 1 in different areas of the noise barrier 5. The two sound insulation devices 1 may be matched differently in order to compensate for differences in wall thickness, form and material of the area of the noise barrier 5 to which they are applied,
[0094] FIG. 16b shows a noise barrier 5 that is provided with a window to break through the otherwise solid form of the wall. To ensure that this window nevertheless contributes to reducing sound transmission, it is provided with a sound insulation device 1. The sound insulation device 1 may therefore be used to create more aesthetically pleasing noise barriers 5 without compromising their functionality.
[0095] The sound insulation device 1 may also be combined with other known noise protection concepts, for example with the noise barrier 5 shown in FIG. 17a with an angled attachment, which serves to influence the diffraction angle of the sound waves diffracted at the upper edge of the noise barrier 5. FIG. 17b shows a complete noise protection enclosure 12, which is provided with sound insulation devices 1 on the outside to reduce sound transmission.
[0096] Corresponding sound insulation devices 1 may also be used on other components that are intended to separate two areas spatially and acoustically. For example, such sound insulation devices may be used for passive noise protection in building faades or noise protection windows. Other possible fields of use in the construction industry include drywalling and doors. Sound insulation devices 1 may also be fitted to machine housings. Mobile noise barriers provided with sound insulation devices 1 may be used on construction sites, or corresponding movable or partition walls in open-plan offices or factories. The exemplary embodiments shown here are therefore not limiting. In particular, these exemplary embodiments may be combined with each other to achieve additional effects. It is obvious to a person skilled in the art that modifications may be made to these exemplary embodiments without departing from the fundamental principles of the subject matter of this patent application, the scope of which is defined in the claims.
