Sound attenuation panel and method of manufacturing sound attenuation panel

Abstract

The invention relates to a sound attenuation panel and a method of manufacturing a sound attenuation panel. A sound attenuation panel is used to reduce noise emanating from a source, such as an engine of an aircraft. The sound attenuation panel includes an open-pore face layer, a back layer, and an intermediate section located between the face layer and the back layer. The intermediate section includes a porous member having a plurality of cavities, and an acoustic metamaterial member positioned in and extending across the cavities.

Description

Technical Field

[0001] This disclosure generally relates to the field of noise reduction devices, and more specifically to noise reduction panels including acoustic metamaterial components. Background Technology

[0002] Noise regulations limit the permissible noise levels at airports. These regulations limit the impact of aircraft noise on communities located near the airport. Various federal and local authorities establish the maximum permissible noise levels for a given time of day. Generally, permissible noise levels are higher during the day and decrease during the evening and nighttime hours. Some airports have microphones installed around their ground to monitor noise levels. Fines or other measures may be used to enforce the regulations.

[0003] Aircraft are designed to reduce noise levels during operation. Noise-reducing materials are used in some aircraft locations within the engine. However, these materials are relatively heavy and increase the aircraft's weight, thus reducing performance and fuel efficiency. Furthermore, these materials are relatively thick, specifically targeting higher frequency noise. These thicker materials are often difficult to design to effectively reduce overall noise and noise at certain frequencies. Additionally, the attachment of thicker materials within the engine can encroach on engine components. Thick materials can also interfere with the integration of engine core mounting accessories.

[0004] Noise reduction measures are also used in other environments. One example includes manufacturing facilities that include industrial equipment that generates high noise levels. Noise attenuation devices are used on and / or in the area surrounding the equipment in an attempt to reduce noise levels. However, existing noise reduction measures have drawbacks and are not effective attenuating noise and / or have additional problems that make their use impractical.

[0005] Therefore, noise reduction devices are needed that attenuate noise and can be designed and manufactured effectively. For aircraft use, the device should be configured to allow use with the aircraft engine without interfering with operation and should also have a relatively light weight. For other applications, the device should be configured to be installed near the noise source. Summary of the Invention

[0006] One aspect relates to an acoustic attenuation panel for reducing noise emitted from a source. The acoustic attenuation panel includes an open-face layer, a back layer, and an intermediate section located between the face layer and the back layer. The intermediate section includes a porous member and an acoustic metamaterial member, the porous member comprising multiple cavities, the acoustic metamaterial member being positioned within the cavities and extending across the cavities. The back layer is configured to be mounted to a surface proximate to the source.

[0007] On the other hand, at least one of the acoustic metamaterial components is located in each cavity.

[0008] On the other hand, the acoustic metamaterial components are positioned within the central section of the cavity and spaced apart from each of the surface and back layers.

[0009] On the other hand, at least two of the acoustic metamaterial components are located within the cavity.

[0010] On the other hand, at least two acoustic metamaterial components located in the cavity are spaced apart.

[0011] On the other hand, each acoustic metamaterial component located in the cavity comprises a different shape.

[0012] On the other hand, the diaphragm is open and extends through the porous structure between the surface layer and the back layer, forming the upper and lower sections of each cavity.

[0013] On the other hand, acoustic metamaterial components are positioned in the upper and lower sections of the cavity.

[0014] On the other hand, sound attenuation panels are mounted on the aircraft's engine nacelle.

[0015] On the other hand, the surface layer, back layer, and intermediate section are flexible to allow the sound attenuation panels to be mounted on the curved surfaces of the aircraft.

[0016] On the other hand, the cavity and acoustic metamaterial components include matching polygonal shapes to allow the acoustic metamaterial components to extend through the entire cavity.

[0017] On the other hand, acoustic metamaterial components are made of polymers.

[0018] On the other hand, porous components include honeycomb structures.

[0019] One aspect relates to an acoustic attenuation panel for reducing noise emitted from a source. The acoustic attenuation panel includes a face layer, a back layer, and a porous member located between the face layer and the back layer. The porous member includes a cavity mounted to a first side of the face layer, mounted to a second side of the back layer, extending through the porous member to have openings at the first and second sides, and an acoustic metamaterial member connected to the porous member and positioned within the cavity, wherein the acoustic metamaterial member is dimensioned to extend across the cavity.

[0020] On the other hand, porous components include honeycomb structures, wherein the cavities have polygonal cross-sectional shapes.

[0021] On the other hand, acoustic metamaterial components include cross-sectional shapes that match the cavity.

[0022] On the other hand, the surface and back layers are made of either metal or carbon fiber, and the sound attenuation panel is made of polymer.

[0023] One aspect relates to a method of manufacturing an acoustic attenuation panel. The method includes: positioning a porous member in an orientation approaching a plurality of cavities, wherein the porous member includes a honeycomb structure having a plurality of cavities extending through the porous member; mounting an acoustic metamaterial member in the cavities, wherein the outer edge of the acoustic metamaterial contacts and abuts the honeycomb structure; mounting a face layer on a first side of the porous member, wherein the face layer is spaced apart from the acoustic metamaterial member; and mounting a back layer on a second side of the porous member, wherein the back layer is spaced apart from the acoustic metamaterial member.

[0024] On the other hand, the method also includes mounting additional acoustic metamaterial components within the cavities of the porous component.

[0025] On the other hand, the method also includes mounting a backing layer onto the surface of the aircraft.

[0026] The features, functions, and advantages already discussed can be realized independently in each aspect or in combination in other aspects, further details of which can be seen in the following description and figures. Attached Figure Description

[0027] Figure 1 It is an isometric view of the aircraft.

[0028] Figure 2 It is a partial cross-sectional perspective view of the engine, including one or more sound attenuation panels mounted on the engine nacelle.

[0029] Figure 3 This is a schematic diagram of the cross-section of the sound attenuation panel.

[0030] Figure 4 yes Figure 3 An exploded view of the sound attenuation panel.

[0031] Figure 4A It is an exploded view of an AMM component with a precisely designed structure.

[0032] Figure 5 This is a schematic side view of an acoustic metamaterial component located within the cavity of a porous component of an acoustic attenuation panel.

[0033] Figure 6 This is a schematic side view of an acoustic metamaterial component located within the cavity of a porous component of an acoustic attenuation panel.

[0034] Figure 7 This is a schematic side view of a portion of an acoustic attenuation panel of an acoustic metamaterial component positioned within a cavity of a porous component.

[0035] Figure 8 This is a schematic side view of a portion of an acoustic attenuation panel of an acoustic metamaterial component positioned within a cavity of a porous component.

[0036] Figure 9 This is a flowchart of a method for manufacturing sound attenuation panels. Detailed Implementation

[0037] Figure 1 An aircraft 100 configured to transport passengers and / or cargo is shown. The aircraft 100 typically includes a fuselage 101 with a flight deck 102 configured to accommodate flight personnel for controlling the aircraft. Engines 20 are mounted on wings 103 located on opposite sides of the fuselage 101. Flight control components 104 (such as flaps) are positioned on the wings 103 to control flight.

[0038] Various different engines 20 can power the aircraft 100. Examples include, but are not limited to, gas turbine engines and turbofan engines. Figure 2 This is a partial cross-sectional view of engine 20. Engine 20 includes an engine core 21 and a fan 22. A nacelle 25 extends around the engine core 21 and the fan 22. The nacelle 25 includes an inlet 26 that directs air to the engine core 21 and the fan 22. A bypass duct 27 is formed between the engine core 21 and the nacelle 25. A portion of the air entering the engine 20 at inlet 26 passes through the fan 23 and enters the engine core 21. The remaining air enters the bypass duct 27 extending around the engine core 21.

[0039] One or more sound attenuation panels 30 are mounted to the inner wall 28 of the nacelle 25 to attenuate noise generated by the engine 20. The sound attenuation panels 30 are positioned at various locations along the inner wall 28, including along one or more of the inlet 26 and bypass duct 27. In some examples, the sound attenuation panels 30 extend completely around the inner wall 28 of the nacelle 25 and have a substantially annular shape. In other examples, the sound attenuation panels 30 extend around a limited portion of the inner wall 28 of the nacelle 25. This arrangement attenuates radiated noise from either the fan 22 or the engine core 21, such as noise caused by the turbine and combustor. In some examples, a single sound attenuation panel 30 is mounted to the inner wall 28. In other examples, two or more sound attenuation panels 30 are joined together and mounted to the inner wall 28.

[0040] Figure 3An acoustic attenuation panel 30 configured to be attached to the nacelle 25 is shown. The acoustic attenuation panel 30 comprises different layers that work together to perform noise attenuation. The acoustic attenuation panel 30 includes an open top layer called a source-facing surface layer 31. In the case of the engine 20, the surface layer 31 faces the interior of the nacelle 25. An impermeable bottom layer called a back layer 32 is configured to be attached to the inner wall 28 of the nacelle 25. An intermediate section 40 is located between the surface layer 31 and the back layer 32. The intermediate section 40 is composed of multiple different components arranged in one or more layers.

[0041] When the sound attenuation panel 30 is installed in the engine 20, the surface layer 31 is exposed and faces outwards toward the interior of the cabin 25. The surface layer 31 is perforated to have openings 33 to allow sound waves to pass through and enter the intermediate section 40. The surface layer 31 may include different constructions, examples including but not limited to perforated plates, wire mesh, and felt metal. The surface layer 31 is made of various materials, including but not limited to various metals and carbon fibers.

[0042] The back layer 32 is a solid component that prevents / reduces the passage of sound waves and forms the back of the sound attenuation panel 30. The back layer 32 includes an outer surface configured to contact and abut against the surface to which it is mounted. The back layer 32 can be made of various materials, including but not limited to various metals and carbon fibers.

[0043] The intermediate section 40 is configured to reduce noise in a frequency range. During use, the sound attenuation panel 30 is fitted with a back layer 32 attached to or facing a surface (such as the inner wall 28 of the engine compartment 25 or a panel near a manufacturing machine). The surface layer 31 faces outward toward the noise source. Sound waves penetrate the openings 33 of the surface layer 31 and enter the cavity 42. Sound energy is dissipated through the viscous heating effect within the cavity 42.

[0044] Figure 4 A schematic exploded view of an acoustic attenuation panel 30 is shown. The acoustic attenuation panel 30 includes a surface layer 31 and a back layer 32. A middle section 40 includes a porous member 41 and an acoustic metamaterial (AMM) member 45. The AMM member 45 is sized to fit within cavities 42 of the porous member 41. In some examples, the AMM member 45 is positioned in each cavity 42 of the porous member 41. In other examples, the AMM member 45 is positioned in a limited number of cavities 42. In one example, the AMM member 45 is uniformly distributed around the porous member 41, and the cavities 42 are also uniformly distributed around the porous member 41. In some examples, the number of AMM members 45 and the number of cavities 42 are the same. In other examples, the number of AMM members 45 and the number of cavities 42 are different.

[0045] The porous member 41 includes a top side 51 and a bottom side 52. The top side 51 is mounted to the surface layer 31, and the bottom side 52 is mounted to the back layer 32. The thickness of the porous member 41, measured between the top side 51 and the bottom side 52, can vary. A cavity 42 extends through the porous member 41 and opens at both the top side 51 and the bottom side 52.

[0046] In such Figure 4 In some of the examples shown, the porous member 41 has a honeycomb structure, wherein the cavities 42 have a polygonal cross-sectional shape. In other examples, the cavities 42 include different shapes, such as, but not limited to, elliptical, circular, and irregular shapes. The cavities 42 extending through the porous member 41 may have the same or different shapes and sizes. The shape and size of the porous member 41 are designed to handle one or more frequency bands of noise. The porous member 41 may be made of a variety of materials, including but not limited to aluminum and glass fiber.

[0047] AMM member 45 is an artificial material designed to control, guide, and manipulate sound waves entering intermediate segment 40. In some examples, AMM member 45 is scaled to be smaller than the wavelength. AMM member 45 may be made of materials including, but not limited to, polymers such as thermoplastic polyurethane (TPU). AMM member 45 is included in cavity 42 to control sound waves by manipulating parameters such as bulk modulus and density.

[0048] Figure 4A An example of an AMM component 45 is shown. The properties of the AMM component 45 are derived from its precisely designed structure. These structures include, but are not limited to, the precise shape, geometry, size, orientation, and arrangement of nanostructures.

[0049] Figure 5 A portion of an acoustic attenuation panel 30 is shown. A porous member 41 is located between a surface layer 31 and a back layer 32. An AMM member 45 is positioned within a cavity 42 of the porous member 41. In this example, the AMM member 45 includes a top section 46 and legs 47. The top section 46 is shaped and sized to extend across the entire cavity 42. In some examples, the outer edge of the top section 46 is attached to the wall of the cavity 42. The legs 47 extend outward from the top section 46 and are secured to the wall of the cavity 42. The AMM member 45 is positioned within the cavity 42 at a depth remote from both the surface layer 31 and the back layer 32. In some examples, all other cavities 42 in the acoustic attenuation panel 30 include a similar configuration with AMM members 45. In other examples, one or more cavities 42 are empty or include different and / or additional AMM members 45. In some examples, the AMM member 45 contacts and abuts one or both of the surface layer 31 and the back layer 32.

[0050] Through the porous member 41, the AMM member 45 may be positioned at the same or different depths within the cavity 42. In some examples, all other cavities 42 in the acoustic attenuation panel 30 include a similar configuration of the AMM member 45. In other examples, one or more cavities 42 are empty or include different and / or additional AMM members 45.

[0051] The dimensions of the AMM member 45 are designed to extend across the cavity 42. In some examples, the cavity 42 and the AMM member 45 include the same cross-sectional shape and dimensions. This allows the AMM member 45 to extend across and contact the wall of the cavity 42. In one specific example, each of the cavity 42 and the AMM member 45 includes a polygonal cross-sectional shape.

[0052] AMM component 45 can be mounted to porous component 41 in various ways. In some examples, AMM component 45 and porous component 41 are constructed and formed together in the same process, such as during additive manufacturing. In some examples, the intermediate segment 40 is constructed using 3D printing technology, wherein the honeycomb porous component 41 and AMM component 45 are produced simultaneously using two different nozzles and two different materials. Additionally or alternatively, AMM component 45 is mounted in cavity 42 using adhesive.

[0053] In some examples, two or more AMM components 45 are positioned within the cavity 42. Figure 6 An example is shown of a pair of AMM members 45a and 45b mounted in a cavity 42. The AMM members 45a and 45b are spaced apart by a gap within the cavity 42. Furthermore, each of the two AMM members 45a and 45b is positioned away from the face layer 31 and the back layer 32. The AMM members 45 may include the same or different shapes and may be made of the same or different materials.

[0054] In such Figure 7 In some examples shown, the sound attenuation panel 30 has a single degree of freedom (SDOF) comprising a surface layer 31, a back layer 32, and an intermediate porous member 41. The cavity 42 is continuous between the surface layer 31 and the back layer 32. In such... Figure 8 In other examples shown, the acoustic attenuation panel 30 has two degrees of freedom (DDOF), wherein the cavity 42 is separated by an open diaphragm 43. Figure 8In the example, the intermediate section 40 includes a first honeycomb layer 41a, an open-cell diaphragm 43, and a second honeycomb layer 41b. An upper section 48 is formed between the face layer 31 and the diaphragm 43, and a lower section 49 is formed between the diaphragm 43 and the back layer 32. An AMM member 45 is positioned in one or both of the upper section 48 and the lower section 49. The diaphragm 43 is open-celled, having openings to allow sound waves to travel from the upper section 48 to the lower section 49. The diaphragm 43 can be made of a variety of different materials, including but not limited to perforated plates, wire mesh, and felt metal.

[0055] The acoustic attenuation panel 30 is used as a Helmholtz resonator. An SDOF design forms a single resonator. A DDOF design couples two Helmholtz resonators in series.

[0056] Figure 9 A flowchart illustrating a method for manufacturing an acoustic attenuation panel 30 is shown. A porous member 41 is positioned for processing (box 200). The porous member 41 includes a honeycomb structure having a through-and-through cavity 42. An AMM member 45 is mounted in the cavity 42 (box 202). The outer edge of the AMM member 45 contacts and abuts the honeycomb structure. A face layer 31 is mounted on a first side of the porous member 41 (box 204). The face layer 31 is spaced apart from the AMM member 45. A back layer 32 is mounted on a second side of the porous member 41 (box 206). The back layer 32 is spaced apart from the AMM member 45.

[0057] The order of the steps in manufacturing the acoustic attenuation panel 30 can vary. In some examples, the AMM member 45 is installed onto the porous member 41 before being installed onto either the surface layer 31 or the back layer 32. In other examples, the porous member 41 is installed onto one of the surface layer 31 and the back layer 32 before the AMM member 45 is installed into the cavity 42.

[0058] The acoustic attenuation panel 30 may include various thicknesses measured between the front layer 31 and the back layer 32. Examples include, but are not limited to, thicknesses ranging from 1 to 3 inches.

[0059] The middle section 40 of the sound attenuation panel 30 is configured to be mounted on various surfaces. In some examples, the sound attenuation panel 30 is flexible to allow mounting on both flat and curved surfaces. In other examples, the sound attenuation panel 30 is rigid.

[0060] The sound attenuation panel 30 can be used to attenuate noise in a variety of different environments. In some examples, the sound attenuation panel 30 is mounted to the inner wall 28 of the engine nacelle 25 of the aircraft 100. In certain examples, the sound attenuation panel 30 is mounted to one or more of the inlet 26 and bypass duct 27. Other mounting locations on the aircraft 100 include, but are not limited to, the internal ducts of the engine 20, the trailing and side edges of the wing 103, and mounting along one or more flight control members 104.

[0061] In another example, the sound attenuation panel 30 is mounted on other vehicles, such as, but not limited to, cars, trucks, ships, spacecraft, rockets, and drones.

[0062] In another example, the sound attenuation panel 30 is installed inside the manufacturing facility near a noise source. In some examples, the sound attenuation panel 30 is installed inside or outside the machine that generates noise. In some examples, the sound attenuation panel 30 is installed on a wall near the machine.

[0063] In some examples, the sound attenuation panel 30 is a single component whose shape and size are designed to extend across a surface. In other examples, the sound attenuation panel 30 consists of two or more segments. These segments are adjacent to each other and connected, for example, by adhesives and mechanical fasteners. In some examples, the different segments are spliced ​​together. In one example where the sound attenuation panel 30 is installed within an engine nacelle 25 having a cylindrical shape, the different components are structurally joined together at splines to form an integral annular shape extending around the engine core 21 and fan 22.

[0064] The acoustic attenuation panel 30 is used to attenuate noise in various environments. The acoustic attenuation panel 30 is relatively light and thin for easy installation in different locations. Furthermore, the acoustic attenuation panel 30 is constructed to provide mass noise reduction. In one example of the acoustic attenuation panel 30 being used on an aircraft 100, the panel achieves excellent acoustic performance, including significant noise reduction during takeoff and landing, with a relatively small increase in weight.

[0065] The term "substantially" in relation to a quantity or measurement means that the characteristic, parameter, or value does not need to be precisely achieved. Instead, deviations or variations, including, for example, tolerances, measurement errors, measurement accuracy limitations, and other factors known to those skilled in the art, can occur in quantities that do not preclude the influence intended to provide the characteristic.

[0066] Of course, the invention may be practiced in ways different from those specifically described herein without departing from its essential characteristics. These embodiments are to be considered illustrative rather than restrictive in all respects, and all variations within the meaning and scope of the appended claims are intended to be included therein.

[0067] Examples of this disclosure may be described in accordance with one or more of the following terms.

[0068] Clause 1. An acoustic attenuation panel for reducing noise emitted from a source, the acoustic attenuation panel comprising:

[0069] Perforated surface layer;

[0070] Back layer;

[0071] The intermediate section located between the surface layer and the back layer, the intermediate section comprising:

[0072] A porous component comprising multiple cavities;

[0073] An acoustic metamaterial component, the acoustic metamaterial component being positioned within the cavity and extending across the cavity; and

[0074] The back layer is configured to be mounted on a surface close to the source.

[0075] Clause 2. The acoustic attenuation panel according to Clause 1, wherein at least one of the acoustic metamaterial components is positioned in each cavity of the cavity.

[0076] Clause 3. The acoustic attenuation panel according to Clause 1, wherein the acoustic metamaterial component is positioned within the central section of the cavity and spaced apart from each of the surface layer and the back layer.

[0077] Clause 4. The acoustic attenuation panel according to Clause 1 further includes at least two acoustic metamaterial components located in the cavity.

[0078] Clause 5. The acoustic attenuation panel according to Clause 4, wherein the at least two acoustic metamaterial components in the cavity are spaced apart.

[0079] Clause 6. The acoustic attenuation panel according to Clause 4, wherein each of the acoustic metamaterial components positioned in the cavity comprises a different shape.

[0080] Clause 7. The acoustic attenuation panel according to Clause 1 further includes a diaphragm that is open and extends across the porous member between the surface layer and the back layer, forming an upper and lower segment of each cavity in the cavity.

[0081] Clause 8. The acoustic attenuation panel according to Clause 7, wherein the acoustic metamaterial component is positioned in the upper and lower sections of the cavity.

[0082] Clause 9. The acoustic attenuation panel as described in Clause 1, wherein the acoustic attenuation panel is mounted on the engine nacelle of the aircraft.

[0083] Clause 10. The acoustic attenuation panel according to Clause 9, wherein the surface layer, the back layer, and the intermediate section are flexible to allow the acoustic attenuation panel to be mounted on the curved surface of the aircraft.

[0084] Clause 11. The acoustic attenuation panel according to Clause 1, wherein the cavity and the acoustic metamaterial component include matching polygonal shapes to allow the acoustic metamaterial component to extend across the entire cavity.

[0085] Clause 12. The acoustic attenuation panel according to Clause 1, wherein the acoustic metamaterial component is constructed of a polymer.

[0086] Clause 13. The acoustic attenuation panel according to Clause 1, wherein the porous component comprises a honeycomb structure.

[0087] Clause 14. An acoustic attenuation panel for reducing noise emitted from a source, the acoustic attenuation panel comprising:

[0088] Surface layer;

[0089] Back layer;

[0090] A porous member located between the surface layer and the back layer, the porous member comprising:

[0091] The first side is installed onto the surface layer;

[0092] The second side is installed onto the back layer;

[0093] A cavity extending through a porous member to have openings at the first and second sides; and

[0094] An acoustic metamaterial component is attached to the porous component and positioned within the cavity, the dimensions of which are designed to extend across the cavity.

[0095] Clause 15. The acoustic attenuation panel according to Clause 14, wherein the porous member comprises a honeycomb structure, and wherein the cavity comprises a polygonal cross-sectional shape.

[0096] Clause 16. The acoustic attenuation panel according to Clause 15, wherein the acoustic metamaterial component includes a cross-sectional shape that matches the cavity.

[0097] Clause 17. The sound attenuation panel as described in Clause 15, wherein,

[0098] The surface layer and the back layer are composed of one of metal and carbon fiber; and

[0099] The acoustic attenuation panel is made of polymer.

[0100] Clause 18. A method of manufacturing a sound attenuation panel, the method comprising:

[0101] The porous component is positioned in an orientation close to the plurality of cavities, the porous component comprising a honeycomb structure having a plurality of cavities extending through the porous component;

[0102] An acoustic metamaterial component is installed in the cavity, wherein the outer edge of the acoustic metamaterial contacts and abuts against the honeycomb structure;

[0103] A surface layer is mounted on the first side of the porous component, wherein the surface layer is spaced apart from the acoustic metamaterial component; and

[0104] The back layer is mounted on the second side of the porous component, wherein the back layer is spaced apart from the acoustic metamaterial component.

[0105] Clause 19. The method according to Clause 18 further includes mounting an additional acoustic metamaterial component in the cavity of the porous component.

[0106] Clause 20. The method described in Clause 18 further includes mounting the backing layer to the surface of the aircraft.

Claims

1. A sound attenuation panel for reducing noise emitted from a source, the sound attenuation panel comprising: Perforated surface layer; Back layer; The intermediate section, located between the surface layer and the back layer, includes: A porous component, the porous component comprising multiple cavities; An acoustic metamaterial component, the acoustic metamaterial component being positioned within the cavity and extending across the cavity; and The back layer is configured to be mounted on a surface close to the source.

2. The sound attenuation panel according to claim 1, wherein, At least one acoustic metamaterial component is positioned in each cavity of the cavity.

3. The sound attenuation panel according to claim 1, wherein, The acoustic metamaterial component is located in the central section of the cavity and is spaced apart from each of the surface layer and the back layer.

4. The acoustic attenuation panel according to claim 1, wherein the acoustic attenuation panel further comprises at least two acoustic metamaterial components located in the cavity.

5. The sound attenuation panel according to claim 4, wherein, The at least two acoustic metamaterial components in the cavity are spaced apart.

6. The sound attenuation panel according to claim 4, wherein, Each of the acoustic metamaterial components located in the cavity comprises a different shape.

7. The acoustic attenuation panel of claim 1, further comprising a diaphragm that is open and extends across the porous member between the surface layer and the back layer to form an upper and lower segment of each cavity in the cavity.

8. The sound attenuation panel according to claim 7, wherein, The acoustic metamaterial component is positioned in the upper and lower sections of the cavity.

9. A sound attenuation panel for reducing noise emitted from a source, the sound attenuation panel comprising: Surface layer; Back layer; A porous component, located between the surface layer and the back layer, comprising: The first side is mounted to the surface layer; The second side is mounted to the back layer; A cavity extending through the porous member to have openings at the first and second sides; and An acoustic metamaterial component, the acoustic metamaterial component being connected to the porous component and positioned within the cavity, the dimensions of the acoustic metamaterial component being designed to extend across the cavity.

10. A method for manufacturing a sound attenuation panel, the method comprising: The porous component is positioned in an orientation close to multiple cavities, the porous component comprising a honeycomb structure having multiple cavities extending through the porous component; An acoustic metamaterial component is installed in the cavity, wherein the outer edge of the acoustic metamaterial component contacts and abuts the honeycomb structure; A surface layer is mounted on a first side of the porous component, wherein the surface layer is spaced apart from the acoustic metamaterial component; as well as A backing layer is mounted on the second side of the porous component, wherein the backing layer is spaced apart from the acoustic metamaterial component.

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