A method and a metamaterial for collecting sound waves

Abstract

The invention relates to a method for collecting sound waves from the environment and / or changing their characteristics and a metamaterial for this process.

Description

[0001] A METHOD AND A METAMATERIAL FOR COLLECTING SOUND WAVES

[0002] Technical Field

[0003] The invention relates to a method for collecting sound waves from the environment and / or changing their characteristics and a metamaterial for this process.

[0004] The present invention relates to a normal and random sound waves router, collector and thus a method of directing and collecting sound waves from different angles, which can be used for passive, resonating or meta-based materials developed for the purpose of directing, isolating, or damping / absorbing sound waves in areas such as construction, architecture, automotive, aviation, space, white goods, machinery industry, etc.

[0005] State of the Art

[0006] Traditional materials such as sponge, felt, textile wastes, glass wool, rock wool, etc. are generally used for sound absorption in the field of acoustics. However, these materials are fairly inefficient due to wavelength constraints, especially at low frequencies (in the range of about 50 Hz-800 Hz). The effective thickness of the material increases as the frequency increases, and the performances of these materials increase as the effective thickness reaches values comparable to the wavelength of the sound.

[0007] Sound absorption is provided by the conversion of sound energy into heat energy in the insulation material. Traditional materials generally provide this energy conversion in three ways. The first is the visco-thermal and scattering effects of the sound in the material as a result of the friction in the cavity and structure, the second is the visco-elastic energy losses caused by the sound pressure in the material due to the deformation elasticity on the elastic particles, and the third is the tortuosity formed by the penetration path length of the sound in the material. However, all these energy conversions are directly related to the effective thickness of the material. The low-frequency sound wave easily passes through the material by partially creating these effects in the material. Therefore, these materials cannot be very efficient at low frequencies. Therefore, researchers are trying to develop effective metamaterials at low frequencies. Metamaterials are artificial structures that do not exist in nature, usually containing micro- or macro-resonance cells of periodic and lower wavelength sizes. The metamaterials can be tuned to the desired frequency (frequency-tuning) depending on the appropriate geometry design and the characteristics of the main materials used. However, metamaterials can generally perform in the narrow band in terms of sound absorption. In order for metamaterials to operate in a wider band, they need to be developed in order to prevent their effects such as having different multi-cell architectures, therefore containing intricate and complex structures that make mass production difficult and decreasing absorption ability at higher frequencies.

[0008] Therefore, research has been carried out on metamaterials, especially in recent years, and various developments have been made on these materials for low frequencies, although they are not yet widely used industrially. Researchers working in the field of acoustics are trying to develop various materials that are effective at low frequencies. Metamaterials, which are one of them, are artificial structures that do not exist in nature, usually containing micro- or macro-resonance cells of periodic and lower wavelength sizes. The metamaterials can be tuned to the desired frequency (frequency-tuning) depending on the appropriate geometry design and the characteristics of the main materials used.

[0009] However, metamaterials can generally perform in the narrow band in terms of sound absorption. In order for metamaterials to operate in a wider band, further developments need to be made in order to eliminate problems such as the necessity of having different multi-cell architectures, therefore the necessity of containing intricate and complex structures that make mass production difficult, and the decrease in absorption ability at higher frequencies. In order for metamaterials to provide high performance, the sound pressure must be strong enough to resonate the material cells, that is, to overcome cell structural inertia (cell mass resistance). Cells designed specifically for lower frequencies operate with less efficiency because they have greater cell mass resistance and / or cannot resonate strongly enough if exposed to low-amplitude sound waves.

[0010] In relation to this, the sound wave must be applied directly to the material cells in order for the metamaterial cells to be efficient. The sound waves with the random incidence angle, which constitute the majority of the sound energy, cannot be effectively covered by the metamaterial.

[0011] CN114255723A discloses a metamaterial for sound reduction. Said metamaterial contains a circular and concentric double case, and while one of these cases is filled with soundabsorbing materials, the other case is arranged to form a labyrinth structure within itself.

[0012] Another metamaterial is disclosed in CN218243835U. Here, channels extending by expanding in the radial direction around a body in the center are used. Said invention can perform multi-directional, multi-band damping at the lower wavelength of this structure.

[0013] An absorbing acoustic metamaterial is disclosed in WO2017093693A1. Here, there are channels extending in the axial and radial direction in the form of a groove depending on the inlets provided on the upper surface of a cylindrical structure.

[0014] All the problems mentioned above have made it necessary to make an innovation in the relevant field as a result.

[0015] Objects of the Invention

[0016] The main object of the invention is to provide a method for taking / collecting both normal and random sound waves from the environment and a metamaterial structure related to this method.

[0017] The object of the invention is to provide a method for changing the characteristics by interfering with normal and random sound waves from the environment and a metamaterial structure related to this method.

[0018] The object of the invention is to increase the sound absorption performance in metamaterials. In particular, it provides efficiency especially in the low frequency region without showing performance decrease at high frequencies.

[0019] The object of the invention is to increase the filtering performance. The object of the invention is to provide a more compact metamaterial by reducing the thickness requirement in metamaterials.

[0020] Brief Description of the Invention

[0021] The present invention basically relates to a method for directing non-normal, that is, random sound waves, as well as normal sound waves, to a common point, for example a metamaterial arranged for the sound wave, especially to the absorption / damping / filtering channels of said metamaterial, and a collector that will provide this directing.

[0022] In said metamaterial, the collector is positioned in the cell inlet of a metamaterial so that one creates at least two different entries for normal and the other for random incident waves. Said inlets preferably direct the sound waves to the same point within the metamaterial, especially to the same channel, through the channels created by the metamaterial and the collector.

[0023] Thus, in addition to normal sound waves, random sound waves are also taken / collected from the environment.

[0024] In addition, the collector ensures that normal and random sound waves are interfered with by directing sound waves especially to a common metamaterial channel with the inlets it provides.

[0025] The interference mentioned here can be carried out constructively or destructively depending on the regulation of the distance between the point where normal and random sound waves enter the metamaterial and the point where they reach the cell channel, and accordingly, significant performance increase can be achieved in absorption or filtering properties. Therefore, the need for larger metamaterials to improve these performances is eliminated and performance can be achieved with much smaller structures.

[0026] Definitions of Figures Describing the Invention

[0027] The figures and related descriptions used to better explain the invention are as follows.

[0028] Figure 1. An isometric image of the assembly of the collector with a metamaterial. Figure la. An isometric image of an embodiment of the collector.

[0029] Figure lb. A top image of Figure la.

[0030] Figure 1c. A cross-sectional view of Figure lb along the A-A axis.

[0031] Figure Id. A sectional image of another embodiment of the collector.

[0032] Figure le. A cross-sectional view along the A-A axis showing the sound wave inlets of

[0033] Figure 1.

[0034] Figure If. A cross-sectional view of Figure 1 along the A-A axis.

[0035] Figure 2. A side image of another embodiment of the assembly of the collector with a metamaterial.

[0036] Figure 3. An isometric image of the router

[0037] Figure 4. An isometric image of the assembly of another embodiment of the collector with the metamaterial.

[0038] Figure 4a. A lower isometric image of the collector in Figure 4.

[0039] Figure 4b. An upper isometric image of the collector in Figure 4.

[0040] Figure 4c. A cross-sectional view of Figure 4b along the A-A axis.

[0041] Figure 5. A dashed isometric image of the metamaterial for the blinding layer.

[0042] Figure 5a. An isometric image of the blinding layer placement of the metamaterial in Figure 5.

[0043] Figure 5b. An isometric image of the section in Figure 4 where the collector will be placed on the metamaterial.

[0044] Figure 5c. An upper image of Figure 5.

[0045] Figure 5d. An image of the installation of the circular- square inlet piece on the metamaterial, which allows the collector in Figure 4 to be placed on the metamaterial in Figure 5.

[0046] Figure 6. A cross-sectional image showing the absorption / damping / filtering mechanism of the embodiment in Figure 2 and Figure 4.

[0047] Figure 6a. A schematic cross-sectional image showing the absorption / damping / filtering mechanism of the embodiment in Figure 5.

[0048] Figure 6b. A schematic cross-sectional image showing the absorption / damping / filtering mechanism of the embodiment in Figure 5c.

[0049] Figure 7. Amplitude-wavelength graphs showing the disruptive interference for various s values.

[0050] Figure 8. Amplitude-wavelength graphs showing the constructive interference for various s values. Figure 9. When there is a device with metamaterial (n+r waves) and there is no device with metamaterial (only n) and experimental sound absorption coefficient.

[0051] Definitions of Components / Pieces / Parts of the Invention

[0052] In order to better explain the invention, the parts and pieces in the figures are numbered and the corresponding numbers are given below.

[0053] 1. Metamaterial

[0054] 1.1. Metamaterial inlet

[0055] 1.2. Cell inlet

[0056] 1.3. Metamaterial upper surface

[0057] 2. Collector

[0058] 2.1. Collector outer surface

[0059] 2.2. Collector inner surface

[0060] 2.3. Inlet Opening

[0061] 2.4. Collector inlet surface

[0062] 2.5. Guide

[0063] 3. Router

[0064] 3.1. Router tip

[0065] 3.2. Router base

[0066] 4. Layer

[0067] 5. Opening layer

[0068] Rn. Normal wave inlet

[0069] Rr. Random wave inlet

[0070] Cn. Normal inlet section

[0071] Cr. Random inlet section

[0072] Ln. Primary distance

[0073] Lr. Secondary distance

[0074] Lc. Total length

[0075] Lcn. Normal inlet channel length

[0076] Cp. Cut-off point n. Normal wave r. Random wave z. Interference zone

[0077] H. Cell

[0078] A. A-A axis

[0079] Detailed Description of the Invention

[0080] The subject matter of the invention relates to a method for collecting sound waves from the environment and / or changing their characteristics and a metamaterial for this process.

[0081] In said method, normal incident waves (n) and random incident waves (r) are collected. Throughout the description, the normal wave (n) is defined as the waves coming at a right angle to the surface where the wave will enter. Random incident waves (r) are waves that come at a different angle from the perpendicular to the surface.

[0082] Said normal incident waves (n) and random incident waves (r) are taken from different inlets from each other and the surface provided in the continuation of these inlets acts as an obstacle and changes the direction of the sound wave and carries both normal incident waves (n) and random incident waves (r) to a common collection point. In the present invention, the inlets of said normal incident waves (n) and random incident waves (r) are defined as normal wave inlet (Rn) and random wave inlet (Rr), respectively.

[0083] Here, the directing is carried out through two different sound waves independent of each other and preferably no interference occurs between normal incident waves (n) and random incident waves (r) until said common point is reached.

[0084] In a preferred embodiment, normal incident waves (n) and random incident waves (r) carried by said two different paths can perform an interference at said common point. In this case, said common point can be called the interference zone (z).

[0085] As a result of said interference, the characteristic of the wave may change. When said wave characteristic change is manipulated as necessary, it can be used for both the absorption / damping and filtering process. During the disclosure of the present invention, it was surprisingly seen that after the sound waves carried by independent paths, normal incident waves (n) and random incident waves (r) are taken from different inlets from each other, by manipulating the distance they travel while reaching the interference zone (z), the interference of said waves can be controlled to be destructive or constructive and absorption / damping or filtering can be performed as desired.

[0086] It has been observed that constructive interferences increase absorption / damping performances by increasing low frequency amplitudes, while destructive interferences offer better filtering performance at higher frequencies.

[0087] Control of the performance of said destructive and constructive interferences can be achieved by the following formula:

[0088] Here Lr and £•« refers to the distance traveled by the sound waves while reaching the interference zone (z) after the entrance. Said refers to the wavelength of normal incident waves (n) and random incident waves (r). It refers to the A wavelength and normal incident waves (n) and random incident waves (r) have equal wavelength. Here s is the wavelength setting parameter selected by the user. According to the wavelength adjustment parameter selection, it is controlled whether the interference is destructive or constructive. With said distance regulation, the desired interference is provided by changing the phases of normal incident waves (n) and random incident waves (r).

[0089] In the studies conducted, it was observed that the interference was destructive when it was selected as 0.68 s 1.32, and when it was selected in a way that it would have a value of s < 9.68 ©?’ s > 1.3-2 other than that, it showed a constructive feature.

[0090] Here, maximum destructive interference s =1, constructive interference s =0 and s =2, s=4 appear in the values of 2n, 4n, and multiples. Intermediate values can be changed according to design goals. A collector (2) and a metamaterial (1) comprising at least one preferably multiple cells may be used to perform the sound wave collection and absorption / damping / filtering processes described above.

[0091] Referring to Figure 1, the metamaterial (1) is preferably arranged as a diagonal, especially rectangular or square, but the area of use can also be provided in different forms according to the structure of the cell (H) or cells (H) to be used, if any, or for aesthetic reasons. Preferably, the metamaterial (1) consists of quarter wavelength multiple cells (H) (MQWM), and preferably said cells (H) have a suitable channel structure. Preferably, the helical channel structure is used. This choice contributes positively to the thickness of the metamaterial.

[0092] The metamaterial is equipped with a large number of quarter wave resonance (QWR) cells (H) with a smooth and continuous spiral design so that they do not reflect back. With these cells, it is possible to provide absorption at the desired low frequencies.

[0093] The metamaterial (1) and the collector (2) equipped with quarter wave resonance (QWR) cells (H) provide a new Herschel- Quincke (HQ) based structure at the entrance with a compatible design. The integrated meta-in-meta structure obtained with these two new metamaterials is called mQWHQM in the sense of multiple QW and HQ metamaterials.

[0094] A collector (2) is placed in the inlet part of said metamaterial (1). The collector (2) comprises an opening (2.3) where the sound waves can enter. The opening (2.3) allows the sound waves to pass into the metamaterial inlet (1.1) of the metamaterial (1). Preferably, the opening (2.3) is placed concentrically in the metamaterial inlet (1.1).

[0095] Preferably, the opening (2.3) and the metamaterial inlet (1.1) are located in the center of the metamaterial (1), but this is not necessary, and these two structures can be provided at different points from the center. In an embodiment of the invention, the metamaterial inlet (1.1) is provided as a square. The characteristic size (edge length of the square) of the metamaterial inlet (1.1) was experimentally chosen as a quarter of the physical length of the metamaterial. These dimensions and forms are given as examples, and the metamaterial inlet (1.1) can be in different geometries such as angular (triangular square, rectangular, trapezoid, parallelogram, etc.) or curved (circle, ellipse, etc.). Preferably, the collector (2) and / or the opening (2.3) are provided in a circular form, but this geometric form can also be provided in different forms according to the area of use or for aesthetic reasons.

[0096] The collector (2) also forms a normal wave inlet (Rn) for the sound waves coming from said opening (2.3) to reach the channels of the cells (H) of the metamaterial (1). Here, the sound waves coming from the opening (2.3) are normal incident waves (n).

[0097] In addition, the collector (2) also forms a random wave inlet (Rr) with the metamaterial (1) itself. The random wave inlet (Rr) is also arranged for the sound waves coming from the opening (2.3), like the normal wave inlet (Rn), to reach the cell (H) of the metamaterial (1), preferably to its channels, if any. Here, the sound waves coming from the random wave inlet (Rr) are random incident waves (r).

[0098] Preferably, the normal wave inlet (Rn) and the random wave inlet (Rr) are arranged to transmit the sound waves independently of each other, without interfering with each other, to the cell (H), especially to the channel.

[0099] The normal wave inlet (Rn) and the random wave inlet (Rr) are arranged to transmit the normal sound waves (n) and the random sound waves (r), respectively, to the same point, preferably, preferably to the same cell (H), especially to the same channel of the metamaterial (1).

[0100] In metamaterials (1) with multiple channels or cells (H), said normal wave inlet (Rn) and random wave inlet (Rr) are also arranged to transmit sound waves to at least some, preferably all, of the channels or cells (H).

[0101] Referring to Figures la-lc, the collector (2) comprises an opening (2.3) and comprises a body around the opening (2.3). Said body comprises the collector outer surface (2.1) and the collector inner surface (2.2). Here, the collector outer surface (2.1) refers to the surface in the direction where the sound wave, especially the normal wave (n), comes from, and the collector inner surface (2.2) refers to the surface in the direction where the random sound wave (r) comes from. Preferably, the collector outer surface (2.1) is provided in a curved especially convex form towards the opening (2.3) so that the incoming waves can be reflected towards the opening

[0102] (2.3). In addition, although the collector outer surface (2.1) can be provided in a planar way, this situation is disadvantageous in terms of directing and reflecting back to the opening (2.3). In addition, this body can be perforated in order to minimize reflections.

[0103] Referring to Figures 1c and Id, the normal incident waves (n) passing through the opening

[0104] (2.3) in the collector (2) are guided by the collector inlet surface (2.4) arranged in the lower part of the opening (2.3).

[0105] In addition, the collector inner surface (2.2) directs random incident waves (r). Here, the collector inlet surface (2.4) and the collector inner surface (2.2) are configured to carry the normal incident waves (n) and random incident waves (r) to the same point, respectively.

[0106] Preferably, the surface extending from the opening (2.3) to the collector inlet surface (2.4) is provided in a curved, especially convex, manner.

[0107] Referring to Figures le and If, the collector (2) is positioned to be placed in the opening (2.3) in the metamaterial inlet (1.1) of the metamaterial (1) as described earlier. A normal wave inlet (Rn) is formed to transmit the normal incident waves (n) between the end of said opening (2.3) and the base of the metamaterial inlet (1.1) within said metamaterial (1).

[0108] Preferably, the collector inlet surface (2.4) is arranged as a surface extending along the base of the metamaterial inlet (1.1). The surface mentioned herein forms a normal inlet section (Cn) for transmitting the normal incident waves (n) within said metamaterial (1), preferably the metamaterial (1) cells (H).

[0109] The collector lower surface (2.2) of the collector (2) is shaped in such a way that another entrance is formed on the opening (2.3) and on the metamaterial inlet (1.1).

[0110] A random wave inlet (Rr) is formed to transmit the random incident waves (r) between the collector lower surface (2.2) and the metamaterial upper surface (1.3) into said metamaterial (1). Preferably, the lower surface (2.2) of the collector is arranged as a surface extending along the upper surface (1.3) of the metamaterial. A random inlet section (Cr) is formed to transmit said surface and random incident waves (r) into said metamaterial (1).

[0111] Normal wave inlet (Rn), random wave inlet (Rr), normal inlet section (Cn) and random inlet section (Cr) are arranged to ensure that normal incident waves (n) and random incident waves (r) go to the same point within the metamaterial.

[0112] Preferably, the wave coming from the normal wave inlet (Rn) is transmitted through the normal inlet section (Cn) into the metamaterial (1), in particular into the cell inlets (1.2) of the cells (H) of the metamaterial (1).

[0113] Preferably, the wave coming from the random wave inlet (Rr) is transmitted through the random inlet section (Cr) into the metamaterial (1), in particular into the cell inlets (1.2) of the cells (H) of the metamaterial (1).

[0114] Referring to Figures le and 3, in the present invention, preferably a guide (3) is placed in the opening (2.3), especially in the metamaterial inlet (1.1). The router (3) is useful in terms of ensuring that the normal sound waves (n) hit the base of the metamaterial (1) and are less reflected and that said normal sound waves (n) are directed into the metamaterial (1), especially the cell (H).

[0115] The router (3) is in a structure that expands from its end to its base. Preferably, the cross- sectional area increases from the tip to the base. While the router tip (3.1) part of the router (3) is in a narrow structure, the router base (3.2) is wider than the router tip (3.1).

[0116] In a preferred embodiment, a curved, preferably concave surface is provided from the router tip (3.1) towards the router base (3.2). Alternatively, the surface can be provided planar, but the curved surface is advantageous in terms of better directing the sound wave. For example, the triangle prism can also be prismatically arranged in the router (3). The router (3) mentioned here can be provided as hollow or full.

[0117] Referring to Figure 4-4c, in a preferred embodiment of the invention, multiple guides (2.5) are arranged on the inner surface (2.2) of the collector. The guides (2.5) provide guidance for transferring random incident waves (r) into the metamaterial (1), especially into the channels of the cell (H), after entering from the random wave inlet (Rr).

[0118] The guides (2.5) preferably extend from the edges of the collector (2) towards the metamaterial inlet (1.1). In addition, the guides (2.5) extend from the collector inner surface (2.2) towards the metamaterial upper surface (1.3). As can be seen in the embodiment in Figure 6, the guides (2.5) can be provided in the random inlet section (Cr). Here, a guided random inlet section (Cr) is formed by the fitting of the guides (2.5) to the random inlet section (Cr).

[0119] Alternatively, the guides (2.5) can be formed on the metamaterial upper surface (1.3) and can form channels from the random wave inlet (Rr) to the metamaterial inlet (1.1) in the random inlet section.

[0120] Although the guides (2.5) preferably extend linearly, they can also be provided in a curved or convex form.

[0121] By guiding the sounds at random incidence angles with different length guides (2.5) added to the sub-region of the collector (2), it is directed to the metamaterial inlet (1.1), which provides an advantage in interference control. The random sound waves (r) travel more than the normal sound waves and undergo constructive or destructive interference with the normal sound waves in the interference zone (z) according to the selected parameter.

[0122] It has been previously explained that the current metamaterial (1) may include channels defining the QW cell (H).

[0123] In this embodiment of the invention, at least part of the upper surface (1.3) of the metamaterial is discharged and the collector inner surface (2.2) of the collector (2) is positioned to be placed in the discharged part, especially its guides (2.5).

[0124] It has been previously explained that the current metamaterial (1) contains cells (H), preferably cells (H) with channels, referring to Figures 5 and 5a. In an alternative embodiment of the invention, the channels extend to the metamaterial inlet (1.1), or the cell (H) is exposed by cutting the metamaterial upper surface (1.3). Preferably, at least the upper part of the channels is exposed in the section where the metamaterial upper surface (1.3) is cut.

[0125] In this embodiment, a blunting process was carried out in the exposed parts of the channels. In the blunting process, at least a portion of the surface of the channel is preferably cut from its tip to a cut-off point (Cp) on the channel. On said cut surface, a layer (4) is placed to fit the cut surface.

[0126] Then, the collector (2) with the guides (2.5) is placed in such a way that its guides (2.5) fit on the metamaterial upper surface (1.3). Thus, the random inlet section (Cr) is transformed into a channel structure.

[0127] Said layer (4) is sized not to prevent the entry of random incident waves (r) guided by the guides (2.5) into the cell (H). Here, if the length of the layer (4) is shorter than the cut-off point (Cp), as in Figure 5a, or if the length of the layer (4) is longer than the cut-off point (Cp), the layer (4) does not stand completely and thus the entry of the random wave (r) is possible.

[0128] In this case, while normal incident waves (n) enter at the end point of said channel, random incident waves (r) enter the cell (H) through the guides (2.5) from the exposed part as a result of the cutting of the channels and the placement of the layer (4). Thus, the normal wave inlet (Rn) and the random wave inlet (Rr) are provided separately from each other. Waves converge at a common point in the channel.

[0129] In this embodiment, as can also be seen in Figures 5-5c, the layer (4) may consist of multiple parts. When said layer (4) is positioned appropriately, they form an opening (2.3) in the middle. In Figures 5a-5c, although these layers (4) are shown in the form of a triangular prism, they can also be formed in different geometries according to the form of the cutting point (Cp) or the metamaterial inlet (1.1).

[0130] Referring to Figure 5d, an opening layer (5) is preferably placed on the layers (4) to adapt the metamaterial inlet (1.1) to the opening (2.3) of the collector (2) for the embodiment in Figures 5 and 5c. Here, since the geometry between the layers (4) is square, the opening layer (5) includes a circular opening on it. Here, the shape of the body can also change according to the geometry formed between the layers (4).

[0131] The collector (2) and the metamaterial (1) can be configured to interfere with the incoming normal incident waves (n) and random incident waves (r) at a common point in the metamaterial (1) in an interference zone (z). For this, the collector (2) and the metamaterial (1) should be dimensioned in order to provide the distance from said normal wave inlet (Rn) to the interference zone (z) and the distances from said random wave inlet (Rr) to the interference zone (z), respectively, in accordance with the following formula.

[0132] Lr = i s^ / 2

[0133] Here, the wavelength is selected according to the s desired destructive or constructive character determined by the user as the setting parameter.

[0134] Here, the primary distance (Ln) also refers to the normal wave emission length, and the secondary distance (Lr) refers to the random wave emission length.

[0135] With reference to Figure 6, where the normal wave (n) enters from the normal wave inlet (Rr) formed by the collector (2) and the metamaterial inlet (1.1). There is a collector inlet surface (2.4) provided in the lower part of the opening (2.3) and extending along the base of the metamaterial inlet (1.1). The collector inlet surface (2.4) and the metamaterial inlet (1.1) form the normal inlet section (Cn) together, where the distance extending from the normal wave inlet (Rn) to the interference zone (z) and including the normal inlet section (Cn) forms the primary length (Ln).

[0136] In addition, the body of the collector (2) extends out of the metamaterial inlet (1.1). The collector inner surface (2.2) and the metamaterial upper surface (1.3) in this part extending out form the random wave inlet (Rr) and the random wave section (Cr), which will take the random incident waves (r) into the metamaterial (1) together. Preferably, the random wave section (Cr) is provided with a channel structure with the guides (2.5) under the collector (2) and the waves coming from the random wave inlet (Rr) are transmitted to the interference zone (z) with the help of the guides (2.5). In this embodiment, the collector (2) does not completely close the metamaterial inlet (1.1) and the random wave section (Cr) is connected to the interference zone (z) from this open part into the metamaterial (1). The distance extending from the random wave inlet (Rr) to the interference zone (z) and including the random inlet channel (Rr) forms the secondary distance (Lr).

[0137] Referring to Figure 6a, the interference mechanism in Figure 5-5c is shown. Here, random incident waves (r) enter directly into the metamaterial (1) from the exposed part of the cell (H) with the help of the cutting / blunting of the cells (H) and / or channels and the layer (4) placed in these parts and the guides (2.5).

[0138] In addition, the collector inner surface (2.2) and the metamaterial inlet (1.1) form the normal inlet section (Cn) together, where the distance extending from the normal wave inlet (Rn) to the interference zone (z) and including the normal inlet section (Cn) forms the primary length (Ln).

[0139] The distance from the center of the opening (2.3) to the end of the metamaterial (1) is defined as the total length (Lc). The total length (Lc) and the normal wave channel length (Lcn) intersect with each other. That is, the normal wave channel length (Lcn) is the length indicating a part of the total length (Lc).

[0140] Referring to Figure 6b, where the collector layer (4) and the collector inner surface (2.2) placed on it and the metamaterial inlet (1.1) form the normal inlet section (Cn) together, where the distance extending from the normal wave inlet (Rn) to the interference zone (z) and including the normal inlet channel (Cn) forms the primary length (Ln).

[0141] In these two embodiments, constructive and destructive interferences can be manipulated by changing the length of the cut part of said channel with the dulling process.

[0142] In the metamaterial subject to the invention, all structures can be produced separately with the same or different main material in a way to be integrated with each other. Structures can be easily assembled by mass production with different methods such as plastic injection, CNC process. In Figure 7, destructive interference is shown, and in Figure 8, constructive interference is shown by simulating for different s values. It is possible to obtain a stronger resonance by amplifying the amplitude of the waves at low frequencies (amplitude amplification) with the constructive interference by defeating the mass inertia of the low-frequency cells. Thus, better absorption of small amplitude sound waves at low frequencies can be achieved. In addition, at high frequencies, due to destructive interference, high-frequency sound waves lose energy by interfering before they can reach the cell. This process may be referred to as high-frequency filtering. This makes the resonating system and metamaterial an effective broadband system at high frequencies. Therefore, all cells can be designed and integrated into the system through constructive and destructive interference in accordance with the purpose.

[0143] In Figure 9, the experimental sound absorption coefficients measured in an impedance absorption system assembly are presented. Metamaterial (1) with a cell width of 4mm and a cell thickness of 20mm was used in the tests. As an example of the system subject to the invention, with these results obtained with (n) and (n+r) when there is no device with (1) metamaterial, approximately 80% and 90% sound absorption is provided in the 200Hz- 1000Hz broadband range, respectively.

Claims

CLAIMS1. A method for collecting sound waves from the environment to an acoustic metamaterial (1), characterized in that normal incident waves (n) and random incident waves (r) arriving independently on the metamaterial (1) are guided through two independent paths to a common point in the cell2. A method according to claim 1, characterized in that said normal incident waves (n) and random incident waves (r) are guided to a common point by a collector (2) generating independent normal wave input (Rn) and random wave input (Rr).

3. A method according to claim 1, characterized in that said normal incident waves (n) and random incident waves (r) are directed to a common point by means of a collector (2) generating independent normal wave inlet (Rn) and random wave inlet (Rr), and a normal wave channel (Cn) and a random wave channel (Cr), respectively, connected to the inputs.

4. A method according to any one of claims 1-3, characterized in that said common point is within a metamaterial inlet (1.1) connected to a cell (H) comprising a metamaterial (1) or within a channel comprising the cell (H).

5. A method according to any of one the preceding claims, characterized in that said common point is an interference zone (z) where normal incident waves (n) and random incident waves (r) will be interfered.

6. A method according to claim 5, characterized in that; the primary distance (Ln) and the secondary distance (Lr) are selected in accordance with the following formula r = to - s^ / 2 wherein the primary distance (Ln) is the distance from said normal wave inlet (Rn) to the interference zone (z), the secondary distance (Lr) is the distance from said random waveinlet (Rr) to the interference zone (z), and the s is a user-selected wavelength adjustment parameter.

7. A method according to claim 6, characterized in that said s value is selected in such a way that it is Q.68 s 1.32.

8. A method according to claim 6, characterized in that said s value is selected in such a way that it it is s < 0.68 or s > 1.32 .

9. A device for collecting sound waves from an environment, characterized in that it comprises the following: a metamaterial (1) having a metamaterial input (1.1) and at least one cell (H) connected to the metamaterial input (1.1) through which the waves are introduced, a collector (2) placed in the metamaterial inlet (1.1), having an opening (2.3) positioned in connection with said metamaterial inlet (1.1), having a surface so as to form a normal wave inlet (Rn) for the transmission of normal incident waves (n) from said opening (2.3) to a point in said metamaterial (1) and a random wave inlet (Rr) for the transmission of random incident waves (r) to said same point by a different path than said normal wave inlet (Rn).

10. A device according to claim 9, characterized in that said collector (2) comprises a surface such that said collector lower surface (2.2) and said metamaterial upper surface (1.3) of said metamaterial (1) together form a random wave inlet (Rr).

11. A device according to claim 9 or 10, characterized in that said collector (2) comprises a surface such that the collector lower surface (2.2) and the metamaterial upper surface (1.1) of said metamaterial (1) form a random inlet section (Cr) to guide random incident waves (r) towards said common point.

12. A device according to any one of claims 9-11, characterized in that it comprises guides (2.5) to be connected from said random wave inlet (Rr) to said common point.

13. A device according to claim 9, characterized in that said collector (2) comprises a surface at the end of the opening (2.3) together with the base of said metamaterial inlet (1.1) to form a normal wave inlet (Rn).

14. A device according to claim 9 or 13, characterized in that said collector (2) comprises a surface at the end of the opening (2.3) and together with the base of said metamaterial inlet (1.1) to form a normal inlet channel (Cr) for guiding normal incident waves (n) towards said common point.

15. A device according to claim 9 or 12, characterized in that said cell (H) comprises a channel with at least a part of the surface of said cell (H) discharged and a layer (4) positioned in said discharged part, said layer (4) being positioned on said collector (2) with said collector inner surface (2.2).

16. A device according to claim 15 , characterized in that said layer (4) consists of multiple parts to form said opening (2.3) when said metamaterial is placed in the discharged part.

17. A device according to claim 9, characterized in that said collector (2) has a collector outer surface (2.1) curved towards said opening (2.3).

18. A device according to claim 9, characterized in that the guiding the normal incidence wave (n) is curved from said opening (2.3) towards said common point.

19. A device according to claim 9, characterized in that it comprises a router (3) positioned in said opening (2.3) and increasing its cross-sectional area towards its base.

20. A device according to claim 18, characterized in that it comprises a surface extending inclined towards the base of said router (3).

21. A device according to claim 9, characterized in that said cell (H) is a quarter wavelength multiple cell (MQWM).

22. A device according to any one of claims 9-21, characterized in that said cell (H) comprises at least one channel associated with the metamaterial inlet (1.1).

23. A device according to claim 22, characterized in that said collector (2) or said metamaterial (1) is configured such that said common point is formed in said channel or cell inlet (1.2).

24. A device according to claim 9 or 22 or 23, characterized in that said common point is an interference zone (z) wherein normal incident waves (n) and random incident waves (r) interfere.

25. A device according to claim 24, characterized in that; the primary distance (Ln) and the secondary distance (Lr) are configured in accordance with the following formulawherein the primary distance (Ln) is the distance from said normal wave inlet (Rn) to the interference zone (z), the secondary distance (Lr) is the distance from said random wave inlet (Rr) to the interference zone (z), and the s is a user-selected wavelength adjustment parameter.

26. A device according to claim 25, characterized in that said s value is selected in such a way that it is Q.68 s <1.32.

27. A device according to claim 25, characterized in that said s value is selected in such a way that it is s < 0.&8 or s > 1.32 .

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