Motorized food processing device with acoustic metamaterials

Abstract

A noise-reducing component for a motorized food processing device is described. The noise-reducing component includes one or more acoustic metamaterials to reduce noise output from the motorized food processing device.

Description

MOTORIZED FOOD PROCESSING DEVICE WITH ACOUSTICMETAMATERIALSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to United States Provisional Patent Application No. 63 / 602,088, filed November 22, 2023, and United States Provisional Patent Application No. 63 / 620,483, filed January 12, 2024, the disclosures of which are hereby incorporated by reference in their entireties.FIELD OF THE INVENTION

[0002] The present disclosure relates to a noise-reducing component for a motorized food processing device and, more particularly, to a noise-reducing component that includes one or more acoustic metamaterials tuned to reduce noise output from the motorized food processing device within a certain frequency range.BACKGROUND

[0003] Home appliances with electric motors, such as, for example, blenders, ice cream makers, and stand mixers can be very loud. A common method of noise reduction is to surround portions of the appliance with foam. However, foam restricts air flow and makes it difficult to cool the motor. Another approach is to seal the motor off from the outside environment. This approach creates similar complications since there is no external airflow available to cool the motor. Some devices are partially sealed and include an exhaust / intake vent that allows external air to flow into the motor and then exit the device. This can provide sufficient air flow for the device’s motor but results in significant noise being released into the environment. A solution is needed to reduce undesirable noise emitted by food processing devices without compromising air flow to and from the motor.SUMMARY

[0004] This disclosure relates to a noise-reducing component for a motorized food processing device. The noise-reducing component includes one or more acoustic metamaterials to reduce noise output from the motorized food processing device. By adjusting the dimensions of the one or more acoustic metamaterials, the acoustic properties of the noise-reducing component can be tuned to reduce noise emitted by the food processing device in a specific frequency range. Additionally, since the presently disclosed acoustic metamaterials permit external airto flow freely to and from the device’ s motor, cooling of the motor is not significantly impacted. Particular configurations of acoustic metamaterials, noise-reducing components, food processing devices that include the acoustic metamaterials, and related methods of use of the disclosed devices may include one or more of the following, in any suitable combination.

[0005] In some aspects, a motorized food processing device is disclosed. The motorized food processing device includes one or more acoustic metamaterials to reduce noise output from the motorized food processing device. The motorized food processing device may also include a motor and a gearbox. In some such implementations, the one or more acoustic metamaterials may be positioned to partially or fully surround the motor and / or the gearbox. In these and other embodiments, the one or more acoustic metamaterials may be positioned to reduce noise generated by the motor and / or the gearbox. The one or more acoustic metamaterials may be tuned to reduce noise output at a frequency of within a range of 1000 Hz - 8000 Hz. The one or more acoustic metamaterials may be positioned to receive sound from a noise-generating component and to reflect sound back to the noise-generating component and / or absorb sound energy through dissipation. The one or more acoustic metamaterials may be in the form of a plurality of slitted tubes, with each slitted tube having a C-shaped crosssection. Each slitted tube may have a wall thickness of between 0.75 - 3 mm and an opening width of between 1.5 - 10 mm. In some such configurations, each slitted tube may have an outer radius of between 0.5 - 2.5 cm. Each slitted tube includes an opening and, in some implementations, the openings are oriented toward a sound source. The one or more acoustic metamaterials may alternatively be in the form of a lattice with a plurality of squares with microperforations .

[0006] In another aspect, a noise-reducing component for a motorized food processing device is disclosed. The noise-reducing component includes at least one geometric structure formed of one or more acoustic metamaterials. The geometric structure may be in the form of one or more slitted tubes. Each slitted tube may have a C-shaped cross-section. In other configurations, a plurality of geometric structures are in the form of a lattice with a plurality of squares with microperforations. There may be between 2-10 geometric structures in the noisegenerating component. In these and other implementations, the one or more acoustic metamaterials are tuned to reduce noise output at a frequency of within a range of 1000 Hz - 8000 Hz. The one or more geometric structures formed of one or more acoustic metamaterials may define an air inlet cover for the motorized food processing device. In other implementations, the one or more geometric structures formed of one or more acoustic metamaterials are positioned within a housing of the motorized food processing device. Inthese and other implementations, the one or more geometric structures formed of one or more acoustic metamaterials are positioned between a motor of the motorized food processing device and an air inlet of the motorized food processing device. In select implementations, the one or more geometric structures permit airflow through the noise-reducing component. The one or more geometric structures may be configured to receive sound from a noise-generating component and to reflect sound back to the noise-generating component and / or absorb sound energy through dissipation.

[0007] In yet another aspect, a method of reducing noise output from a motorized food processing device is disclosed. The method includes coupling a noise-reducing component to a motorized food processing device having a motor and a gearbox. The noise-reducing component includes a plurality of geometric structures formed of one or more acoustic metamaterials.

[0008] In a further aspect, a noise-reducing component for a motorized food processing device is described. The noise-reducing component includes a geometric structure formed of one or more acoustic metamaterials. The geometric structure is in the form of a slitted tube with a length and a C-shaped cross-section. Dimensions of the geometric shape vary continuously and linearly along its length.

[0009] In some implementations, at a first end, the geometric structure has a first wall thickness and a first opening width and, at a second opposing end, the geometric structure has a second wall thickness and a second opening width, and the first wall thickness is unequal to the second wall thickness and the first opening width is unequal to the second opening width. In these and other implementations, the first wall thickness is greater than the second wall thickness and the first opening width is less than the second opening width. The geometric structure may be formed by injection molding or by an extrusion technique.

[0010] A reading of the following detailed description and a review of the associated drawings will make apparent the advantages of these and other structures. Both the foregoing general description and the following detailed description serve as an explanation only and do not restrict aspects of the disclosure as claimed.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Reference to the detailed description, combined with the following figures, will make the disclosure more fully understood, wherein:

[0012] FIG. 1A shows a perspective view of a food processing device outfitted with a noisereducing component, in accordance with some embodiments of this disclosure;

[0013] FIG. IB shows a side view of the food processing device shown in FIG. 1A;

[0014] FIG. 1C shows a cross-sectional view of the food processing device shown in FIG. 1A;

[0015] FIG. 2A shows a perspective view of a noise-reducing component, in accordance with some embodiments of this disclosure;

[0016] FIG. 2B shows a rear view of the noise-reducing component shown in FIG. 2B;

[0017] FIG. 2C shows a cross-sectional view of the noise-reducing component shown in FIG. 2A;

[0018] FIG. 3A shows a cross-sectional view of a motorized food processing device with a noise-reducing component, in accordance with some implementations of this disclosure;

[0019] FIG. 3B shows a perspective view of the motorized food processing device shown in FIG. 3A;

[0020] FIG. 3C shows an exploded view of the motorized food processing device shown in FIG. 3B.

[0021] FIG. 4A shows an illustration of a sample acoustic metamaterial in the shape of a slitted tube, in accordance with some embodiments of this disclosure;

[0022] FIGS. 4B1-4B4 show illustrations of a sample acoustic metamaterial in the shape of a slitted tube with dimensions that vary continuously and linearly along its length, in accordance with some embodiments of this disclosure;

[0023] FIG. 5 shows an illustration of a sample acoustic metamaterial in the shape of nested slitted tubes, in accordance with some embodiments of this disclosure;

[0024] FIG. 6 shows an illustration of a sample acoustic metamaterial in the shape of a lattice formed of a plurality of squares with microperforations, in accordance with some embodiments of this disclosure;

[0025] FIG. 7 shows an illustration of a sample acoustic metamaterial in the shape of a spiral tube, in accordance with some embodiments of this disclosure;

[0026] FIG. 8 illustrates a method of reducing noise output from a motorized food processing device;

[0027] FIG. 9 illustrates features of a sample acoustic wave propagating, measured at various points in space;

[0028] FIG. 10 illustrates the theoretical specific acoustic impedance for a sample acoustic metamaterial configured in accordance with some embodiments of the present disclosure;

[0029] FIG. 11 illustrates a graph of measured frequency content for a particular food processing device with and without acoustic metamaterials as disclosed herein; and

[0030] FIG. 12 illustrates a plot of specific acoustic impedance as a function of frequency and length for a sample acoustic metamaterial configured in accordance with an implementation of the present disclosure.DETAILED DESCRIPTION

[0031] In the following description, like components have the same reference numerals, regardless of different illustrated embodiments. To illustrate embodiments clearly and concisely, the drawings may not necessarily reflect appropriate scale and may have certain structures shown in somewhat schematic form. The disclosure may describe and / or illustrate structures in one embodiment, and in the same way or in a similar way in one or more other embodiments, and / or combined with or instead of the structures of the other embodiments.

[0032] In the specification and claims, for the purposes of describing and defining the invention, the terms “about” and “substantially” represent the inherent degree of uncertainty attributed to any quantitative comparison, value, measurement, or other representation. The terms “about” and “substantially” moreover represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. Open-ended terms, such as “comprise,” “include,” and / or plural forms of each, include the listed parts and can include additional parts not listed, while terms such as “and / or” include one or more of the listed parts and combinations of the listed parts. Use of the terms “top,” “bottom,” “above,” “below” and the like helps only in the clear description of the disclosure and does not limit the structure, positioning and / or operation of the disclosed devices in any manner.

[0033] A noise-reducing component for a motorized food processing device is disclosed, along with related devices, assemblies, and methods. The disclosed devices, assemblies, and methods utilize acoustic metamaterials to reduce noise output from a motorized food processing device (alternatively referred to herein as a “food processing device” or “device”).

[0034] Metamaterials are materials configured with specific geometries that influence the behavior of waves that encounter the metamaterial. Metamaterials usually contain a single geometric structure (called a “unit cell” or “meta-atom”) that is repeated numerous times over a large area. The geometric structure of the metamaterial influences the behavior of waves that contact the metamaterial, specifically how the waves are reflected, absorbed, and / or transmitted). Metamaterials can be designed to influence light waves, electromagnetic waves, or sound waves in a particular manner. Metamaterials that influence sound waves are known as “acoustic metamaterials.” Acoustic metamaterials are more space-efficient than traditionalsound-absorbing foams and can be mass produced using conventional techniques, such as injection molding or extrusion.

[0035] The geometry of acoustic metamaterials can be adjusted (or “tuned”) to, for example, have a high absorption coefficient at specific frequencies. Acoustic absorption operates on the principles of dissipating sound energy via heat, which can reduce the total sound heard by a user. Theoretical models can be used to predict the behavior of acoustic metamaterials. Some sample acoustic metamaterials are discussed below in further detail.

[0036] FIG. 1A shows a perspective view of a food processing device 10 having a noisereducing component 100 containing one or more acoustic metamaterials. FIG. IB shows a side view of the food processing device 10 and FIG. 1C shows a cross-sectional view of the food processing device 10 taken along line A — A shown in FIG. IB. The food processing device 10 may be any type of motorized food processing device, such as a blender, ice cream maker, mixer, micro puree machine, or other type of food processing device capable of blending, mixing, pureeing, slicing, dicing, chopping, grating, shaving, peeling, grinding, squeezing, folding, kneading, or any suitable combination of the foregoing. As described below in detail, the food processing device 10 may include one or more acoustic metamaterials (in the noisereducing component 100 or elsewhere) to reduce noise output from the motorized food processing device 10.

[0037] The food processing device 10 may include a sound source 200, such as a motor and / or a gearbox, as shown in FIG. 1C. Various types of motors and gearboxes for food processing devices are known in the relevant art and the disclosed noise-reducing component 100 can be used in connection with food processing devices having any type of known AC or DC motor and associated gear componentry. The noise-reducing component 100, which includes one or more acoustic metamaterials, may be positioned proximate to the motor and / or the gearbox, and may be positioned to partially or fully surround the motor and / or the gearbox, as desired. In these and other embodiments, the one or more acoustic metamaterials may be positioned to reduce noise generated by the motor and / or the gearbox.

[0038] In contrast to other types of sound- absorbing materials that may be arranged in the interior of a food processing device, perhaps on an interior surface of a housing, the disclosed acoustic metamaterials may form, or be part of, a component that is not arranged in the interior of the food processing device. For example, such component may be a component that is separate and discrete from the housing of the food processing device 10, such as an air inlet cover for the food processing device 10. Such component may be permanently or removablyattached to the housing, and in some embodiments may be integrally formed as part of the housing.

[0039] As shown in FIG. 1C, the noise-reducing component 100 may be positioned to receive acoustic energy (i.e., sound or noise) from a sound source 200 (e.g., a motor and / or gearbox). The overall direction of sound propagation (Ds) through the noise-reduction component 100 is illustrated in FIG. 1C. As shown in FIG. 1C, Dsoriginates from a sound source 200 (e.g., a motor and / or a gearbox) and travels through the noise-reduction component 100 into an external environment. If desired, the noise-reducing component 100 may be configured to permit air to freely pass between the external environment and the sound source 200, which may provide heat dissipation advantages. The noise-reducing component 100 may be attachable to and removable from the food processing device 10. However, in other configurations, the noise-reduction component 100 is fixedly joined to the housing of the food processing device 10.

[0040] FIG. 2A illustrates a perspective view of a noise-reducing component 100. FIG. 2B shows a rear view of the noise-reducing component 100 of FIG. 2A and FIG. 2C shows a cross- sectional view of the noise-reducing component 100 taken along line A — A of FIG. 2B. As shown in FIGS. 2A-2C, the noise-reducing component 100 includes a plurality of geometric structures 102a, 102b, 102c (referred to generally at times as “geometric structure(s) 102”). The geometric structures 102 are formed of one or more acoustic metamaterials. The geometric structures 102 may be positioned within the noise-reducing component 100 such that the geometric structures 102 receive sound from a noise-generating component and reflect sound back to the noise-generating component and / or absorb sound energy through dissipation. Although FIGS. 2A-2C show three geometric structures 102 formed of one or more acoustic metamaterials, more or less than three geometric structures 102 are also possible and contemplated herein. For example, in some implementations, the noise-reducing component 100 includes between 2-10 geometric structures 102.

[0041] The geometric structures 102 may be arranged in the noise-reducing component 100 such that the geometric structures 102 may be proximate to, and / or partially or fully surround a noise-generating component (e.g., sound source 200 shown in FIG. 1C). The geometric structures 102 may be spaced to permit airflow through the noise-reducing component 100, if desired. In select implementations, a plurality of geometric structures 102 formed of one or more acoustic metamaterials define an air inlet cover for the motorized food processing device 10. However, in other implementations, one or more geometric structures 102 formed of oneor more acoustic metamaterials may be positioned elsewhere within the motorized food processing device 10.

[0042] For example, FIGS. 3A-3C illustrate a motorized food processing device 10 with a noise-reducing component 100. The noise-reducing component 100 includes at least one geometric structure 102 formed of one or more acoustic metamaterials, as described herein. As shown in FIGS. 3A-3C, the noise-reducing component 100 is positioned within a housing 12 of the motorized food processing device 10 between a sound source 200 (e.g., motor and / or gearbox) and an air inlet 14. The noise-reducing component 100 may be free-standing within the housing 12 and need not be affixed to housing walls or other components of the housing 12, if desired. The noise-reducing component 100 may be attached to a base 16 of the housing 12 and positioned between the sound source 200 and the air inlet 14 in the overall direction of sound propagation (Ds) from the sound source 200 through the device 10.

[0043] The dimensions of the geometric structures 102 may be selected to provide desired acoustic reflection and / or dissipation. The one or more acoustic metamaterials may be tuned to reduce noise output at a frequency of within a range of 1000 Hz - 8000 Hz. In select configurations, the one or more acoustic metamaterials are tuned to reduce noise output at a frequency of within a range of 2200 - 2600 Hz.

[0044] The geometric structures 102a, 102b, 102c shown in FIGS. 2A-2C are in the form of a plurality of slitted tubes. Each slitted tube may have a C-shaped cross- section. FIG. 4A illustrates a sample slitted tube geometric structure 102 formed of an acoustic metamaterial. As shown in FIG. 4A, the slitted tube geometric structure 102 has an outer radius (‘a’), an inner radius (‘n’), a wall thickness (‘t’), and an opening width (‘w’). In some configurations, the wall thickness (t) is between 0.75 - 3 mm and the opening width (w) is between 1.5 - 10 mm. In these and other configurations, each slitted tube geometric structure 102 has an outer radius (a) of between 0.5 - 2.5 cm. In some cases, the opening of each slitted tube is oriented toward a sound source (e.g., sound source 200). The slitted tube geometric structure 102 shown in FIG. 4A has constant or approximately constant dimensions along its length (‘L’).

[0045] FIGS. 4B1-4B4 show a geometric structure 102 formed of an acoustic metamaterial in the form of a slitted tube with a C-shaped cross-section and dimensions that vary continuously and linearly along its length (L). FIG. 4B1 shows a perspective view of the geometric shape 102. FIG. 4B2 shows a side view of the geometric shape 102. FIG. 4B3 shows a cross-section of the geometric shape 102 taken along line C-C of FIG. 4B2. FIG. 4B4 shows a cross-section of the geometric shape 102 taken along line D-D of FIG. 4B2. As shown in FIGS. 4B1-4B4, the geometry of the geometric structure 102 varies along its length. At a first end (see cross-section C-C shown in FIG. 4B3), the geometric structure 102 has a first wall thickness (ti) and a first opening width (wi). At a second opposing end (see cross-section D-D shown in FIG. 4B4), the geometric shape 102 has a second wall thickness (t2) and a second opening width (W2). The first wall thickness (ti) is unequal to the second wall thickness (t2) and the first opening width (wi) is unequal to the second opening width (W2). Specifically, the first wall thickness (ti) is greater than the second wall thickness (t2) and the first opening width (wi) is less than the second opening width (W2). The geometric structure 102 illustrated in FIGS. 4B1- 4B4 may be formed by injection molding or an extrusion technique, if desired. Having nonconstant dimensions along its length may impart advantageous noise-reducing properties to the geometric structure 102. For example, a geometric structure with non-constant dimensions along its length may provide noise reduction in a broader frequency range as opposed to a geometric structure with constant dimensions. Since specific frequency outputs can vary between units due to tolerances of the motor, including a geometric structure with non-constant dimensions along its length may provide improved noise reduction for some motorized food processing devices.

[0046] The geometric structure(s) 102 may take forms other than as shown in FIGS. 4A-4B4. For example, FIG. 5 shows a sample geometric structure 102 formed of one or more acoustic metamaterials in the shape of three nested slitted tubes. FIG. 6 shows a sample geometric structure 102 formed of one or more acoustic metamaterials in the shape of a lattice formed of a plurality of squares with microperforations. FIG. 7 shows a sample geometric structure 102 formed of one or more acoustic metamaterials in the shape of a spiral tube.

[0047] The noise-reducing component 100 (including geometric structure(s) 102) may be formed of any suitable solid material. In some implementations, the noise-reducing component 100 and / or geometric structures 102 are formed of or include, at least in part, a polymeric material, composite, metal, or metal alloy. In select implementations, the noise-reducing component 100 is formed of steel, aluminum, polycarbonate, polyethylene terephthalate (PET), polyethylene terephthalate ethylene (PETE), polyethylene (PE), high-density polyethylene (HDPE), low-density polyethylene (HDPE), polyvinyl chloride (PVC), polypropylene (PP), and / or polystyrene (PS).

[0048] FIG. 8 illustrates a method of reducing noise output from a motorized food processing device (method 300) using any of the devices and techniques disclosed herein. As shown in FIG. 8, method 300 includes coupling a noise-reducing component to a motorized food processing device (302). The noise-reducing component may be the noise-reducing component 100 described herein. In particular, the noise-reducing component may include aplurality of geometric structures formed of one or more acoustic metamaterials. The motorized food processing device may have any features of the motorized food processing device 10 described herein. For example, the motorized food processing device may have a motor and a gearbox. The motorized food processing device may be at least one selected from the group of: an ice cream maker, a blender, a mixer, a micro puree machine, and a type of food processing device capable of blending, mixing, pureeing, slicing, dicing, chopping, grating, shaving, peeling, grinding, squeezing, folding, and / or kneading. In these and other cases, method 300 may reduce the sound emitted by the food processing device by at least 2 dB or at least 4 dB.

[0049] While the disclosure particularly shows and describes certain embodiments, those skilled in the art will understand that various changes in form and details may exist without departing from the spirit and scope of the present application as defined by the appended claims. The scope of this present application intends to cover such variations. As such, the foregoing description of implementations of the present application does not intend to limit the full scope conveyed by the appended claims.Additional Configurations and Examples

[0050] Although some particular embodiments of the disclosed motorized food processing devices containing one or more acoustic metamaterials (and associated noise-reducing components) have already been described in detail, additional and alternative implementations are also possible. Specifically, the acoustic metamaterials can be tuned to reflect and / or absorb desired sound frequencies. Techniques for adjusting dimensions of the disclosed acoustic metamaterials to reduce or eliminate particular sound frequencies are described below, along with experimental testing data, and possible methods of use.

[0051] As previously mentioned, food processing devices can create undesirable noise. Additionally, each type of food processing device has a unique frequency content. That is, each motorized device may produce different acoustic energy at different frequencies. Humans are more perceptive to sound frequencies of between 3 and 5 kHz. Furthermore, frequencies between 1 and 8 kHz have been shown to be particularly problematic in motorized food processing devices. It could be helpful for the disclosed acoustic metamaterials to reduce noise in a frequency band produced by the food processing device to which it is coupled without reducing air flow around the motor.

[0052] Acoustic metamaterials are space-efficient, meaning that the size of an acoustic metamaterial is small when compared to the wavelength of sound that it absorbs. FIG. 9 illustrates features of a sample acoustic wave propagating, measured at various points in space.The wavelength of the sound refers to the length of the wave in space to complete 1 full cycle.This is computed with Equation 1 :Wavelength = speed of wave / frequency

[0053] For a sound wave having a frequency of 100 Hz and travelling in air at 343 m / s (the speed of sound at room temperature), the wavelength of the wave will be 3.4 meters. Traditional foams used to absorb sound are generally configured to be !4 the wavelength of the desired sound to be absorbed. So, to absorb a 100 Hz sound wave, the foam would need a thickness of approximately one meter. Acoustic metamaterials can absorb sound waves using significantly less space than traditional foams.

[0054] Equations used to tune the geometry of acoustic metamaterials are known in the art. For example, the paper “Acoustic Metamaterial Capsule for Reduction of Stage Machinery Noise” published in the Journal of the Acoustical Society of America provides equations for tuning sample acoustic metamaterials.Example 1

[0055] An acoustic metamaterial was created with dimensions specifically tuned to reflect sound waves of approximately 2400 Hz. The acoustic metamaterial was in the form of a plurality of slitted tubes, each having a C-shaped cross-section. The slitted tubes each had an outer diameter of 22 mm, an inner diameter of 18.38 mm, and a throat width of 5 mm. FIG. 10 shows the theoretical specific acoustic impedance of this acoustic metamaterial.

[0056] Three slitted tubes of the aforementioned acoustic metamaterial were arranged to form a noise-reducing component. The frequency content of a food processing device (without the noise-reducing component containing acoustic metamaterial) was measured and the frequency content of the same food processing device was then tested again with the noise-reducing component coupled to the food processing device. The measured frequency spectrum of this example is shown in FIG. 11. Frequency spectrum “A” shown in FIG. 11 is representative of the data obtained without the noise-reducing component and frequency spectrum “B” is representative of the data obtained with the noise-reducing component.

[0057] Additional testing shows that this noise-reducing component reduced the overall sound output of the food processing device by 4.8 dB(A), which is a 22% reduction in psychoacoustic loudness. It is important to note that the decibel scale is logarithmic. The smallest audible sound is 0 dB. A sound that is 10 dB is ten times more intense than a sound of 0 dB and asound that is 30 dB is 1,000 times more powerful than a 0 dB sound. A noise reduction of 4.8 dB(A) is therefore significant and non-trivial.Example 2

[0058] A sample acoustic metamaterial was proposed with dimensions specifically tuned to reflect sound waves of approximately 3844 Hz. FIG. 12 illustrates a plot of specific acoustic impedance as a function of frequency and length for the sample acoustic metamaterial. The sample acoustic metamaterial was in the form of a slitted tube with a C-shaped cross-section and dimensions that vary continuously and linearly along its length. The sample acoustic metamaterial was configured to reduce noise output in a frequency range of from 3878 Hz - 3769 Hz.

[0059] At a first end of the sample acoustic metamaterial, the dimension of the outer diameter was 13.88 mm, the inner diameter was 9.88 mm, and the throat width was 2 mm. At the opposed end of the sample acoustic metamaterial, the dimension of the outer diameter was 13.93 mm, the inner diameter was 12.22, and the throat width was 4.3 mm. As shown in FIG. 12, the target frequency lined up fairly well with the minima of the acoustic impedances, and also provided a decently wide band of tolerance as the dimensions change.

Claims

CLAIMS1. A motorized food processing device comprising: one or more acoustic metamaterials to reduce noise output from the motorized food processing device.

2. The motorized food processing device of claim 1, wherein the motorized food processing device further comprises: a motor; and a gearbox, wherein the one or more acoustic metamaterials are positioned to reduce noise generated by the motor and / or the gearbox.

3. The motorized food processing device of claim 1, wherein the one or more acoustic metamaterials are tuned to reduce noise output at a frequency of within a range of 1000 Hz - 8000 Hz.

4. The motorized food processing device of claim 1, wherein the one or more acoustic metamaterials are in the form of a plurality of slitted tubes.

5. The motorized food processing device of claim 4, wherein each slitted tube has a C-shaped cross-section.

6. The motorized food processing device of claim 4, wherein each slitted tube has a wall thickness of between 0.75 - 3 mm and an opening width of between 1.5 - 10 mm.

7. The motorized food processing device of claim 6, wherein each slitted tube has an outer radius of between 0.5 - 2.5 cm.

8. The motorized food processing device of claim 5, wherein each slitted tube comprises an opening and the openings are oriented toward a sound source.

9. The motorized food processing device of claim 1, wherein the one or more acoustic metamaterials are in the form of a lattice comprising a plurality of squares with microperforations .

10. The motorized food processing device of claim 1, wherein the one or more acoustic metamaterials are positioned to receive sound from a noise-generating component and to reflect sound back to the noise-generating component and / or absorb sound energy through dissipation.

11. A noise-reducing component for a motorized food processing device, the noisereducing component comprising: a geometric structure formed of one or more acoustic metamaterials.

12. The noise-reducing component of claim 11, wherein the noise-reducing component includes a plurality of geometric structures in the form of slitted tubes.

13. The noise-reducing component of claim 12, wherein each slitted tube has a C- shaped cross-section.

14. The noise-reducing component of claim 11, wherein the noise-reducing component comprises a plurality of geometric structures in the form of a lattice comprising a plurality of squares with microperforations.

15. The noise-reducing component of claim 11, wherein there are between 2-10 geometric structures in the noise-reducing component.

16. The noise-reducing component of claim 15, wherein the one or more acoustic metamaterials are tuned to reduce noise output at a frequency of within a range of 1000 Hz - 8000 Hz.

17. The noise-reducing component of claim 11, wherein geometric structure formed of one or more acoustic metamaterials defines an air inlet cover for the motorized food processing device.

18. The noise-reducing component of claim 11, wherein the geometric structure formed of one or more acoustic metamaterials is positioned within a housing of the motorized food processing device.

19. The noise-reducing component of claim 18, wherein the geometric structure formed of one or more acoustic metamaterials is positioned between a motor of the motorized food processing device and an air inlet of the motorized food processing device.

20. The noise-reducing component of claim 11, wherein the geometric structure permits airflow through the noise-reducing component.

21. The noise-reducing component of claim 11, wherein the geometric structure is configured to receive sound from a noise-generating component and to reflect sound back to the noise-generating component and / or absorb sound energy through dissipation.

22. A method of reducing noise output from a motorized food processing device, the method comprising: coupling the noise-reducing component of claim 1 to a motorized food processing device having a motor and a gearbox.

23. A noise-reducing component for a motorized food processing device, the noisereducing component comprising: a geometric structure formed of one or more acoustic metamaterials, wherein the geometric structure is in the form of a slitted tube with a length and a C-shaped cross-section, and dimensions of the geometric shape vary continuously and linearly along its length.

24. The noise-reducing component of claim 23, wherein: at a first end, the geometric structure has a first wall thickness and a first opening width, at a second opposing end, the geometric structure has a second wall thickness and a second opening width, and the first wall thickness is unequal to the second wall thickness and the first opening width is unequal to the second opening width.

25. The noise-reducing component of claim 24, wherein the first wall thickness is greater than the second wall thickness and the first opening width is less than the second opening width.

26. The noise-reducing component of claim 23, wherein the geometric structure is formed by injection molding.

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