Sound absorption body and method for its production

Abstract

A sound-absorption body (100) for attenuating frequencies below 500Hz, having a sound-absorption surface (101) configured to be exposed in an environment (200) where acoustic emissions (50) to be attenuated are present. A plurality of through-openings (102) is formed in the sound-absorption surface (101 ), and a corresponding plurality of acoustic attenuation elements (110) are provided, each defining a blind acoustic attenuation path. The acoustic attenuation elements (110) extend from an opposite side of the sound-absorption surface (101 ) each starting from a through opening (102). Each blind acoustic attenuation element (110) extends along an axis (111) having a predetermined length, has a main diameter (112), comprises a plurality of annular partitions (113) having an internal hole (114) with a restricted diameter (115) less than or equal to 95% of the main diameter (112) and terminates with a closed end (116). The invention provides a sound-absorption body with low thickness, high absorption of low-frequency acoustic emissions and ease of manufacture. The restricted diameter (115) can be adjustable, and the axis (111) of the blind acoustic attenuation path can include an initial curve, so that the acoustic attenuation elements (110) are parallel to the sound-absorption surface (101 ).

Description

TITLESOUND ABSORPTION BODY AND METHOD FOR ITS PRODUCTIONDESCRIPTIONScope of the invention

[0001] The present invention relates to the field of acoustic engineering and more specifically it refers to a sound-absorption body for attenuating acoustic emissions in an environment.

[0002] In particular, the sound-absorption body is designed to attenuate low-frequency acoustic emissions below 500Hz.

[0003] The invention also relates to a method for the production of such a sound-absorption body.

[0004] The invention also relates to modular elements for the construction of this sound-absorption body.Brief overview of the known technique

[0005] Sound-absorption materials and devices are known, including porous materials such as polymer foams or composite panels, which can be used to attenuate acoustic emissions in both working environments and public spaces. These materials are normally used to attenuate acoustic vibrations above 1kHz, unless high thicknesses are used to attenuate lower frequencies as well.

[0006] There are also materials that include resonant devices. Resonant materials and devices have demonstrated excellent attenuation capabilities at even lower frequencies, but generally greater than 500Hz. The use of these materials for absorption at lower frequencies (< 500 Hz) is possible, but at the expense of a considerable thickness requirement and frequency-selective behaviour. Some resonating attenuation devices are described below.

[0007] US2023 / 215411A1 describes an acoustic absorber consisting of a micro-perforated plate and a cavity behind the micro-perforated plate that defines a curved main acoustic propagation path in which acoustic filters with different cut-off frequencies are arranged in order of cut-off frequencies, from the highest to the lowest. The main acoustic propagation path and the succession of acoustic filters provide a phase delay so that the microperforated plate effectively absorbs broadband acoustic waves. The curved shape ensures that the overall structure is relatively thin.

[0008] US2022 / 036871A1 relates to a system for constructing modular quarter-wavelength resonators, configured to form arrays of such resonators interconnected with each other and capable of forming channels within them. The modules are blocks that can be fitted together and may include straight channels and curved channels, allowing resonators of any desired configuration to be formed. The length of the resonator and, consequently, the resonance frequency can be easily designed by adjusting the number of blocks used for a particular resonator. This document allows for good attenuation at frequencies above 500Hz, giving examples for frequencies between 800Hz and 1600Hz. However, at low frequencies below 500Hz, quarter wavelength resonators have been shown to attenuate specific frequencies in a very narrow range. Therefore, to achieve sufficient attenuation for broad-spectrum noise at low frequencies, it would be necessary to build a very large number of quarter wavelength resonators each for one specific frequency.

[0009] CN110322868A describes a resonator to be placed in pipelines to reduce noise. The resonator has a variable diameter constriction to adjust the resonance frequency and achieve the value that attenuates the noise. The narrowing is achieved by a variable diameter shutter. A noise detector produces a signal that is processed by a processor, which controls a stepper motor that acts on the shutter shaft, adjusting its diameter according to the noise signal received.

[0010] It is desirable to attenuate low-frequency acoustic emissionsbecause they can be particularly annoying and can even cause physical discomfort . Such vibrations can occur, for example:- in industrial environments, produced by heavy machinery, cranes, compressors, motors, turbines and other large industrial equipment; - in civil and industrial environments, such as ventilation systems, transformers and electrical power equipment, passing vehicles such as lorries, buses and industrial vehicles, aeroplanes, trains, underground trains, excavation work.

[0011] These vibrations are poorly attenuated by building structures, so it is desirable to have sound-absorption bodies capable of attenuating them in environments where they penetrate or are generated.Summary of the invention

[0012] An object of invention is therefore to provide a sound-absorption body to attenuate acoustic emissions in an environment that is easy to implement and allows the attenuation of low-frequency acoustic emissions below 500Hz.

[0013] It is also an object of the present invention to provide a soundabsorption body that allows for reduced thicknesses.

[0014] Another object of the present invention is to provide a soundabsorption body that allows it to be easily adapted according to the characteristics of the acoustic emissions to be attenuated.

[0015] A further object of the invention is to provide a method for producing such a sound-absorption body.

[0016] It is also an aim of the invention to provide modular elements for the construction of such a sound-absorption body as well as providing a system of such sound-absorption body and such modular elements.

[0017] These and other objects are achieved by a sound-absorption body for attenuating frequencies below 500Hz having a surface configured to be exposed to sounds in an environment, wherein:- said sound-absorption body comprises a plurality of through- openings on the surface,- said sound-absorption body comprises a plurality of acoustic attenuation elements each defining a blind acoustic attenuation path extending from an opposite side of the surface from a respective through opening of the through openings, and- each blind acoustic attenuation element:- extends along an axis having a predetermined shape and a predetermined length,- has a main diameter,- comprises a plurality of annular partitions having an internal hole with a diameter less than or equal to 95% of the main diameter,- terminates with a closed end.

[0018] Thanks to the invention, at low frequencies below 500Hz it is possible to cover a wide frequency spectrum with a single acoustic attenuation element. Therefore, with just a few different types of sound attenuation elements it is possible to substantially attenuate the acoustic emissions at frequencies below 500Hz. This is a major advantage over quarter-wavelength-resonator-type attenuators, which at low frequencies below 500Hz are able to attenuate specific frequencies in a very narrow range.

[0019] According to one possible embodiment of the invention, each blind acoustic attenuation element comprises tubular portions connected in succession and having the main diameter as their internal diameter, the tubular portions comprising the annular partitions internally.

[0020] According to one possible embodiment of the invention, the axis of the blind acoustic attenuation element has at least an initial curved portion so that the attenuation element has a portion of the axis after the initial curved portion disposed in a plane parallel to the surface of the body.

[0021] According to one possible embodiment of the invention, the axisof the blind acoustic attenuation element has a curved shape, optionally spiral- or helical-shaped.

[0022] According to a possible embodiment of the invention, the tubular portions comprise an adjustment module for adjusting the restricted diameter of the internal holes of the annular partitions, so that the restricted diameter can be modified between a first value and a second value by actuating the adjustment module.

[0023] According to one possible embodiment of the present invention, the adjustment module comprises an adjustment actuating element accessible from outside the tubular portions.

[0024] According to one possible embodiment of the invention, the adjustment module comprises a mechanism configured like a photographic shutter inside the body, operated by a lever having an end accessible from outside the tubular portions.

[0025] In possible embodiments of the invention, the acoustic attenuation element comprises tubular connecting portions connected in succession to adjustment modules of the restricted diameter of the internal holes of the annular partitions, so that the restricted diameter can be modified between a first value and a second value.

[0026] In possible embodiments of the invention, the tubular portions, or the connecting tubular portions or the adjustment modules, comprise threaded portions for connection with each other or to the through openings.

[0027] In possible embodiments of the invention, the tubular portions or tubular connecting portions are curved in shape, optionally one of the tubular portions being an initial curved portion.

[0028] In possible embodiments of the invention, the adjustment modules comprise a shutter mechanism and a shutter mechanism actuating element accessible from outside the adjustment module.

[0029] In possible embodiments of the invention, the shutter mechanism comprises curved connecting rods configured to be linked together and toengage holes in a perforated ring that is integral with the actuating element.

[0030] In possible embodiments of the invention, the axis of the blind acoustic attenuation actuator element has at least an initial curved portion so that the axis of the attenuation element has a downstream portion after the initial curved portion disposed in a plane parallel to the sound-absorption surface.

[0031] In possible embodiments of the invention, the initial curved portion comprises at least one annular partition with said restricted diameter hole.

[0032] In possible embodiments of the invention, the acoustic attenuation elements have a shape comprising curved portions and extend according to a plane parallel to the sound-absorption surface; optionally, the acoustic attenuation elements are spiral- or helical-shaped.

[0033] According to a possible embodiment of the invention, the soundabsorption modules are arranged in a matrix on the body.

[0034] According to a possible embodiment of the invention, the body comprises a panel having a predetermined thickness.

[0035] According to another aspect of the invention, a method for producing a sound-absorption body as defined above comprises:- providing a body having a surface,- making a plurality of through openings on said surface,- creating a plurality of acoustic attenuation elements, each defining a blind acoustic attenuation path extending from an opposite side of said surface starting from a through opening of said through openings, wherein each blind acoustic attenuation element- extends along an axis having a predetermined shape and a predetermined length,- has a main diameter,- comprises a plurality of annular partitions having an internal hole with a diameter less than or equal to 95% of the main diameter,- terminates with a closed end,wherein said acoustic attenuation elements each defining a blind acoustic attenuation path re made by arranging a plurality of modular elements comprising:- a first modular element comprising a curved portion;- a plurality of tubular modular elements, each having at least one of said annular partitions inside;- a blind terminal modular element.

[0036] According to yet another aspect of the invention, a system of sound-absorption elements is provided comprising:- a body having a surface and a plurality of through openings on said surface,- a plurality of modular elements comprising:- a first modular element comprising a curved portion;- a plurality of tubular modular elements having a main diameter and at least one annular partition having an internal hole with a diameter less than or equal to 95% of the main diameter;- a blind terminal modular element,said modular elements being configured to be assembled in series to form a plurality of acoustic attenuation elements extending from opposite sides of said surface, each starting from a through opening of said through openings, such that each acoustic attenuation elementextends along an axis having a predetermined shape and a predetermined length,terminates with a closed end.Brief description of the drawings

[0037] The above summary of the various aspects of the invention will be illustrated below with reference to some embodiments, by way of example and not limitative, with reference to the accompanying figures in which:Figure 1 shows a perspective view of a sound-absorption body placed in an environment;Figure 2 shows an enlarged partial view of the sound-absorption body of Figure 1 ;Figure 3 shows a cross-sectional view of a portion of a possible embodiment of the sound-absorption body according to the invention;Figure 4 shows a cross-sectional view of a portion of an embodiment of the sound-absorption body of Figure 3;Figure 5 shows modular elements that can be used to make a soundabsorption body similar to that of Figure 4;Figure 6 shows a cross-sectional view of a portion of another embodiment of the sound-absorption body of Figure 3;Figure 7 shows a perspective view of a possible embodiment of an acoustic attenuation element similar to that shown in Figure 6;Figure 8 shows a further variant of an acoustic attenuation element according to the invention. Figures 9 and 10 show a portion of the acoustic attenuation element of Figure 7 that forms a partition with a variable cross-section in the maximum diameter and reduced diameter position, respectively.Figure 11 shows an exploded view of a portion of the acoustic attenuation element of Figure 8;Figures 12 to 16 show components for creating the acoustic attenuation element of Figure 8, shown in an exploded view in Figure 11 ; Figure 17 shows a sectional view of a further possible embodiment of an acoustic attenuation element according to the invention;Figure 18 shows an attenuation diagram obtained by a single acoustic attenuation element of the sound absorption body of the invention;Figure 19 shows a perspective view of another possible embodiment of an acoustic attenuation element similar to that shown in Figures 3, 4 and 6;Figure 20 shows a sectional perspective view of an acoustic attenuation element similar to that of Figure 19;Figures 21 and 22 show perspective views from the front and rear, respectively, of a sound-absorption body according to the invention comprising different embodiments of acoustic attenuation elements.Detailed description of some embodiments

[0038] With reference to Figs. 1, 2, and 3, a sound-absorption body 100, particularly usable for attenuating frequencies below 500 Hz, comprises a surface 101 configured to be exposed to an environment 200 in which it is desirable to attenuate acoustic emissions 50, such as a private or public place, an office work environment, or an industrial environment. Fig. 1 shows, for example, an office in which the sound-absorption body 100 is exposed, for example, adjacent to a wall 210 or integrated into it, such as a plasterboard wall or a partition of another type.

[0039] The sound-absorption body 100 comprises, starting from surface 101, a plurality of through openings 102. The sound-absorption body 100 also comprises a plurality of acoustic attenuation elements 110 (e.g. Fig. 3), each defining a blind acoustic attenuation path extending from an opposite side of said surface 101 , each starting from a through opening of the through openings 102.

[0040] In particular, each acoustic attenuation element 110 extends along an axis 111 having a predetermined shape and a predetermined length, as described below.

[0041] Furthermore, each acoustic attenuation element 110 has a main diameter 112 and comprises a plurality of annular partitions 113 having a main internal hole 114 with a restricted diameter 115 less than or equal to 95% of the main diameter 112.

[0042] Finally, each blind acoustic attenuation element 110 terminates with a closed end 116.

[0043] The sound-absorption body 100 may comprise a support body 103, for example a panel 103 having a predetermined thickness, traversed by said through openings 102, which are, for example, cylindrical holes. Thethrough-openings 102 may be arranged in a matrix or other regular pattern over the entire surface 101 or randomly, until a predetermined porosity is achieved, i.e. the ratio between the sum of the openings and the surface area 101.

[0044] This solution attenuates acoustic emissions 50 that reach surface 101, in particular low-frequency emissions, such as those below 500Hz. The acoustic attenuation elements 110, distributed over the soundabsorption body 100 on the opposite side to surface 101 and each defining a blind acoustic attenuation path, as they all have a closed end 116, may be identical or different in terms of the number of partitions 113 and the restricted diameter 115 of the internal hole 114 of the partitions 113, so as to cover the frequencies to be absorbed.

[0045] The blind acoustic attenuation element 110 can be made in various ways, for example by moulding two moulded half-shells and welding them together, or by 3D printing, in a manner not described in greater detail as it can be achieved using techniques known to a person skilled in the art.

[0046] According to one possible embodiment of the invention, shown in Fig. 4 or Fig. 5, which is particularly advantageous in terms of modularity, each blind acoustic attenuation element 110 comprises tubular portions 120 connected in succession to each other, having the main diameter 112 as their internal diameter, and having the annular partitions 113 inside them.

[0047] The tubular portions 120 can be connected in succession by means of end edges 123 and 124 that can be engaged by screw connection, as shown in Fig. 4, or welded or glued, or connected by socket or bayonet coupling, or otherwise fixed together in other ways known to a person skilled in the art.

[0048] The first element 120 can also be fixed to the panel 103 using the screw end 123, which engages a screw seat 104 in the panel 103 or, in any case, a seat facing from surface 101 through holes 102.

[0049] A final tubular portion 121 is provided, having a blind end 116 and a screw end 124, for fastening to the last tubular portion 120.

[0050] In this way, the blind acoustic attenuation element 110 can be easily created by combining different or identical elements 120, in varying numbers, to achieve an attenuation effect on specific frequencies. In particular, acoustic attenuation elements 110 with specific restricted diameters 115 of the holes 114 of the partitions 113 can be assembled together.

[0051] The tubular portions 120, 121 of Fig. 4 or Fig. 5 can also be made, for example, by additive printing, or as welded printed half-shells, or in any other way known to a person skilled in the art.

[0052] In one possible embodiment of the invention, shown in Fig. 6, the axis 111 of said blind acoustic attenuation element 110 has at least an initial curved portion 117, in particular elbow-shaped, so that said attenuation element 110 has a downstream portion 118 of said axis 111 after said initial curved portion 117 arranged in a plane parallel to said surface 101 of said body.

[0053] The curved portion has been found not to alter the attenuation capabilities of the acoustic attenuation element. Therefore, the acoustic attenuation element 110, which has an axis 111 with a first curved portion 117 and then a portion 118 parallel to the surface 101, is capable of providing high attenuation capacity as if it had a straight axis, but with the advantage of occupying minimal space in the direction orthogonal to the surface 101.

[0054] As also described below, similarly to what is illustrated in Figures 4 and 5, the blind acoustic attenuation element 110 with axis 111 having an initial elbow section 117 may comprise modular tubular sections 120 and 121. In this case, an initial elbow-shaped tubular portion 122 may be used, as shown, for example, in the case of Fig. 7, described below.

[0055] The tubular portions 120 shown in Figs. 4 and 5 are shown straight but they also can be curved, and the acoustic attenuation element 110, formed by a number of tubular portions connected in succession, may have any shape.

[0056] In one possible embodiment of the invention, shown in Fig. 7, the tubular portions 120 are curved, and there is a first elbow-shaped tubular portion 122 and a terminal tubular portion 121. Fig. 5 shows a particular spiral shape of the acoustic attenuation element 110, which is particularly advantageous in terms of minimum space requirements and considerable development of the axis 111 , chosen to absorb specific sound frequency spectra.

[0057] Other shapes are obviously possible, for example, spiral or sinuous shapes, or irregular shapes, whether they develop with an axis 118 of various shapes but in a plane parallel to the surface 101, although it is not excluded that some or all sections may be in directions orthogonal to the surface 101. An example is described below with reference to Fig. 19.

[0058] For example, if wall 210 of room 200 has a rear cavity, as can be the case with plasterboard and similar false walls, the development of the acoustic attenuation elements 110 starting from each opening 102 can also be orthogonal to surface 101 , so as to significantly increase porosity to sound. On the other hand, if the sound-absorption body 100 needs to be as thin as possible, the development of the acoustic attenuation elements 110 starting from each opening 102 can be parallel to the surface 101, thanks to the elbow shape 117 of the axis 111, and, in the case of tubular portions 120, the use of elbow-shaped tubular portions 122, still achieving high attenuation at the frequencies of the acoustic emissions to be attenuated with less bulk.

[0059] In a possible advantageous embodiment of the invention, shown in Fig. 8, the tubular portions 120 may comprise an adjustment module 125 for the restricted diameter 115 of the internal holes 114 of the annular partitions 113, so that the restricted diameter 115 can be adjusted between a first value and a second value by actuating the adjustment module 125, as shown in Figs. 9 and 10.

[0060] In particular, the adjustment module 125 may comprise an actuating element 126 for adjusting the restricted diameter 115 of theinternal holes 114 of the annular partitions 113, accessible from outside the tubular portions 120 by means of its end 126a which protrudes from a slot 129 in the adjustment module 125.

[0061] In particular, in one possible embodiment of the invention, the adjustment module 125 may comprise a shutter mechanism 130, for example substantially in the shape of a photographic shutter, inside the adjustment modules 25 of the tubular portions 120, actuated by an actuating element 126 having a lever end 126a accessible from outside said tubular portions 120.

[0062] As shown in greater detail in the exploded view of Fig. 11, the adjustment module 125 can be formed by two annular shells 127 and 128, also visible in Fig. 14 and Fig. 16, respectively, configured to interlock with each other by means of projections and recesses 127b and 128b and to enclose the shutter mechanism 130. Each adjustment module 125 has screw seats 127a and 128a, made in the annular shells 127 and 128, and configured to engage by screwing with screw ends 141 and 142 of tubular connecting portions 140, as also shown in Fig. 12. The tubular connecting portions may have an internal diameter equal to the main diameter and may be straight or curved. In addition to the screw ends, other forms of releasable engagement may be provided, as already mentioned above, which can be easily implemented by a person skilled in the art.

[0063] In particular (again fig. 11), the shutter mechanism 130 comprises curved connecting rods 131 , having end pins 131 a and end holes 131b, configured to be linked together and engage holes 133a of a perforated ring 133 which is integral with the actuating element 126.

[0064] Fig. 13 shows a variant of the curved connecting rods 131 , with two pins 131a, configured to engage in holes made at the two ends of corresponding connecting rods not shown, to be coupled alternately with each other. The pins 131 a facing the annular shell 128 can engage in seats 128d that act as a stable rotation seat, visible in Fig. 16.

[0065] The actuating element 126 slides into the slot 129 formed bynotches 127c and 128c made on the annular shells 127 and 128, respectively. The rotation of the perforated ring by means of the actuating element 126, overcoming the resistance of the pins 131a in the holes 131b, determines the relative rotation of the curved connecting rods 131, and therefore the variation in the restricted diameter 115 of the hole 114, as shown in Figs. 9 and 10.

[0066] According to one possible embodiment of the invention, the tubular portions 120, 121 , such as those in Fig. 5 or Fig. 11 , may be curved or elbow-shaped. For example, as shown in Fig. 17, an acoustic attenuation element 110 similar to that in Fig. 8 is made with an initial elbow-shaped tubular portion 122. Therefore, the acoustic attenuation element 110 of Fig.17 combines the advantages already described for the embodiments of Figs. 4, 6 and 8, which are not repeated here for the sake of simplicity.

[0067] Thanks to the invention, at low frequencies below 500Hz it is possible to cover a broad frequency spectrum with a single sound attenuation element 110. Therefore, with just a few different types of sound attenuation elements it is possible to substantially attenuate the acoustic emissions at frequencies below 500Hz. For example, as shown in Fig. 18, an acoustic attenuation element 110, which was 205 mm long and with ten constriction elements 114 has shown significant attenuation in the frequency range between 200 and 400Hz. A quarter-wavelength attenuator of equivalent length, as is known, would have attenuated very narrowly only one frequency.

[0068] Again, as an example, Fig. 19 shows a possible embodiment of the invention in which a modular acoustic attenuation element 110 similar to those already shown and described in Figs. 3, 4, and 6 is made with both straight modules, such as those in Fig. 5, and curved or elbow modules. In particular, the acoustic attenuation element 110 of Fig. 19 may comprise an initial curved tubular portion 122 similar to that of Fig. 6 of the modular type, a central straight tubular portion 120, and a blind curved terminal portion 121. Although not shown in Fig. 19, these tubular portions are designed to be screwed together, for example with threaded joints. However, for allembodiments of the invention, where provided, the modular tubular portions may also be connected in an assemblable manner so as to form the soundabsorption body 100 in other ways that are easily implementable by a person skilled in the art, such as interlocking or snap-fit.

[0069] With reference to Fig. 20, the modular elbow tubular portion 122 may also comprise a plurality of annular partitions 113 having an internal hole 114 in the elbow axis section 117. The same applies to the blind elbow tubular end portion 121.

[0070] In particular, in a possible embodiment shown in Fig. 20, an internal hole 114 may also be present flush with the surface 101 in order to allow the attenuation of certain frequencies. In fact, the internal hole 114 at surface 101 can allow, with the same overall dimensions of the soundabsorption body, the formation of a larger overall resonant cavity. This possible variant is also applicable to all embodiments of the invention.

[0071] Obviously, with the modularity of the tubular portions of Figs. 19 and 20, acoustic attenuation elements 110 of any shape can be made. The curved portions help, in particular, to prevent the acoustic attenuation elements 110 from being too bulky in the direction orthogonal to surface 101 , but also in the direction parallel to surface 101. For example, with modular curved tubular elements, acoustic attenuation elements 110 such as those shown in Fig. 7 can be made.

[0072] In this regard, Figs. 21-22 show a perspective view of an exemplary sound-absorption body 100 comprising a panel 103 with acoustic attenuation elements 110 of various shapes made according to the invention applied to each through opening 102. In particular, variants of the invention arranged in a single sound-absorption element 100 are shown, specifically those in Figs. 4, 7, 8 and 17.

[0073] The representation in Figs. 21-22 shows how the presence of straight tubular portions extends orthogonally to surface 101 and on an opposite side of it, allowing for limited space on the opposite side of surface 101 in a direction parallel to surface 101 itself. Therefore, straight acousticattenuation elements 110 can be arranged parallel to each other, thus achieving a higher density of straight acoustic attenuation elements 110 at the expense of a greater overall depth of the sound-absorption body 100. On the other hand, it can be seen that the presence of curved tubular portions allows for a limited extension on the opposite side of surface 101 in a direction orthogonal to surface 101 itself and a greater extension in a direction parallel to surface 101 itself. Therefore, acoustic attenuation elements 110 with an initial curved portion or with multiple curved portions can allow many of them to be arranged parallel to surface 101, and thus have a lower density of straight acoustic attenuation elements 110 to the advantage of a lower overall depth of the sound-absorption body 100.

[0074] The above description of embodiments of the invention, and related examples, is capable of showing the invention from a conceptual point of view so that others, using known technology, can modify and / or adapt these embodiments in various applications without further research and without departing from the inventive concept, and therefore it is understood that such adaptations and modifications will be considered equivalent to the embodiments described. The means and materials for performing the various functions may be of various kinds without departing from the scope of the invention. It is understood that the expressions or terminology used are purely descriptive and, therefore, not limiting.

Claims

CLAIMS1. A sound-absorption body (100) for attenuating frequencies below 500Hz having a sound-absorption surface (101) configured to be exposed to sounds in an environment (200) where acoustic emissions (50) to be attenuated are present,wherein said sound-absorption body (100) comprises a plurality of through-openings (102) on said sound-absorption surface (101), wherein said sound-absorption body (100) further comprises a plurality of acoustic attenuation elements (110), each defining a blind acoustic attenuation path extending from an opposite side of said soundabsorption surface (101) starting from a respective through opening (102) of said through openings,wherein each acoustic attenuation element (110):- extends along an axis (111) having a predetermined length;- has a main diameter (112);- comprises a plurality of annular partitions (113) having an internal hole (114) with a restricted diameter (115) less than or equal to 95% of the main diameter (112);- terminates with a closed end (116).

2. The sound-absorption body (100) as per claim 1, wherein said acoustic attenuation element (110) comprises tubular portions (120) connected in succession and having said main diameter (112) as their internal diameter, said tubular portions (120) comprising said annular partitions (113) internally.

3. The sound-absorption body (100) as per claim 2, wherein said tubular portions (120) comprise an adjustment module (125) of said restricted diameter (115) of the internal holes (114) of said annular partitions (113), so that said restricted diameter (115) can be modified between a first value and a second value.

4. The sound-absorption body (100) as per claim 1, wherein said acoustic attenuation element (110) comprises tubular connecting portions (140) connected in succession to tubular portions internally comprising said annular partitions (113).

5. The sound-absorption body (100) as per claim 1, wherein said acoustic attenuation element (110) comprises tubular connecting portions (140) connected in succession to adjustment modules (125) of said restricted diameter (115) of the internal holes (114) of said annular partitions (113), so that said restricted diameter (115) can be modified between a first value and a second value.

6. The sound-absorption body (100) as per claims 2 to 5, wherein said tubular portions (120), or said tubular connecting portions (140) or said adjustment modules (125) comprise threaded portions for connection to other tubular portions (120), or tubular connecting portions (140) or to said through openings.

7. The sound-absorption body (100) as per claims 2 to 5, wherein said tubular portions (120, 121) or said connecting tubular portions (140) comprise curved tubular portions, optionally one of said curved tubular portions being an initial curved portion (122).

8. The sound-absorption body (100) as per claims 3 or 5, wherein said adjustment modules (125) comprise a shutter mechanism (130) and an actuating element (126) of said shutter mechanism (130) accessible from outside said adjustment module (125).

9. The sound-absorption body (100) according to claim 8, wherein said shutter mechanism (130) comprises curved connecting rods (131) configured to be linked together and to engage holes (133a) of a perforated ring (133) that is integral with said actuating element (126).

10. The sound-absorption body (100) according to any of the previous claims, wherein said axis (111) of said blind acoustic attenuation element (110) has at least an initial curved portion (117) such that said axis (111 ) of said attenuation element (110) has a downstream portion (118) after said initial curved portion (117) arranged in a plane parallel to said sound-absorption surface (101).

11. The sound-absorption body (100) as per claim 10, wherein said initial curved portion (122) comprises at least one said annular partition (113).

12. The sound-absorption body (100) according to any of the previous claims, wherein said acoustic attenuation elements (110) have a shape comprising curved portions and extend according to a plane parallel to said sound-absorption surface (101), optionally said acoustic attenuation elements (110) are spiral-shaped.

13. A method for making a sound-absorption body (100) comprising: - providing a support body (103) having a surface (101 ),- making a plurality of through openings (102) through said surface (101),- making a plurality of acoustic attenuation elements (110) each defining a blind acoustic attenuation path extending from an opposite side of said surface (101 ) starting from a respective through opening of said through openings (102), wherein each acoustic attenuation element:- extends along an axis (111) having a predetermined shape and a predetermined length,- has a main diameter (112),- comprises a plurality of annular partitions (113) having an internal hole (114) with a restricted diameter (115) less than or equal to 95% of the main diameter (112),- terminates with a closed end (116),wherein said acoustic attenuation elements (110) each defining a blind acoustic attenuation path are made by arranging a plurality of modular elements comprising:- a first modular element (122) optionally comprising a curved portion;- a plurality of tubular modular elements (120) each having at least one of said annular partitions (113) inside;- a blind terminal modular element (121 ).

14. A sound-absorption system comprising:- a support body (103) having a surface (101) and a plurality of through openings (102) on said surface (101),- a plurality of modular elements (120) comprising:- a first modular element (122), optionally comprising a curved portion;- a plurality of tubular modular elements having an internal main diameter (112) and at least one annular partition (113) having an internal hole (114) with a restricted diameter (115) less than or equal to 95% of the main diameter (112);- a blind terminal modular element (121 ),said modular elements being configured to be assembled in series to form a plurality of acoustic attenuation elements (110) configured to extend from an opposite side of said surface (101) starting from a respective through opening of said through openings (102), such that each acoustic attenuation element (110):- extends along an axis (111) having a predetermined shape and a predetermined length,- terminates with a closed end (116).

15. The sound-absorption system according to claim 14, wherein said tubular portions (120) comprise an adjustment module (125) of said restricted diameter (115) of the internal holes (114) of said annular partitions (113), so that said restricted diameter (115) can be modified between a first value and a second value.

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