An acoustic double fishnet using Helmholtz resonators

Murray, Alasdair; Summers, Ian R.; Sambles, J. R.; Hibbins, Alastair P.

doi:10.1121/1.4892859

Cited by 11 publications

(10 citation statements)

References 18 publications

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“…S13), which creates cavities between the membrane and the perforated sheet. To study the effect of Helmholtz resonance (42) on the membrane, we systematically investigated the single-hole and multihole Helmholtz resonator models both experimentally and theoretically (figs. S14 and S15).…”

Section: Fundamental Characteristics Of Tasmentioning

confidence: 99%

A highly sensitive, self-powered triboelectric auditory sensor for social robotics and hearing aids

et al. 2018

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The auditory system is the most efficient and straightforward communication strategy for connecting human beings and robots. Here, we designed a self-powered triboelectric auditory sensor (TAS) for constructing an electronic auditory system and an architecture for an external hearing aid in intelligent robotic applications. Based on newly developed triboelectric nanogenerator (TENG) technology, the TAS showed ultrahigh sensitivity (110 millivolts/decibel). A TAS with the broadband response from 100 to 5000 hertz was achieved by designing the annular or sectorial inner boundary architecture with systematic optimization. When incorporated with intelligent robotic devices, TAS demonstrated high-quality music recording and accurate voice recognition for realizing intelligent human-robot interaction. Furthermore, the tunable resonant frequency of TAS was achieved by adjusting the geometric design of inner boundary architecture, which could be used to amplify a specific sound wave naturally. On the basis of this unique property, we propose a hearing aid with the TENG technique, which can simplify the signal processing circuit and reduce the power consuming. This work expresses notable advantages of using TENG technology to build a new generation of auditory systems for meeting the challenges in social robotics.

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Section: Fundamental Characteristics Of Tasmentioning

confidence: 99%

A highly sensitive, self-powered triboelectric auditory sensor for social robotics and hearing aids

et al. 2018

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“…2, that the dispersion becomes linear. In that limit, the dispersion is simply captured by an effective index of refraction, which is readily extracted from the small κ limit of (25), Ω 2 ∼ (4β/V)|κ| 2 . Together with (5) we obtain the large effective index…”

Section: Effective Indexmentioning

confidence: 99%

“…When using the asymptotic approach to generate the solutions induced by sources, it is particularly important to note that the form of the source can lead to differences in the asymptotic scaling of the solution. It is tempting to simply introduce a source-like term directly into the discrete network model (25), but the form of such a term needs to be derived so one can go precisely from the continuum level to the discrete system. In free space, i.e., in the absence of any walls, the above forcing would obviously yield an O(1) response (namely the free-space Green's function).…”

Section: Waves Induced By a Distribution Of Sourcesmentioning

confidence: 99%

“…Building on a rich history of using acoustic resonators to influence sound propagation (e.g., in the context of filters [30], bubbly liquids [5] and sound transmission [11]), the field of metamaterials has inspired numerous novel applications [9,10], including ultrathin metasurface acoustic absorbers for sound insulation [4,17], media with negative effective properties [12,21,23], soda-can metamaterials [22] demonstrating sub-wavelength lensing, and fishnet acoustic metamaterials for broadband tuneable sound absorption [6,25].…”

Section: Introductionmentioning

confidence: 99%

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Asymptotic Modeling of Phononic Box Crystals

Vanel¹,

Schnitzer²

2019

SIAM J. Appl. Math.

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We introduce phononic box crystals, namely arrays of adjoined perforated boxes, as a threedimensional prototype for an unusual class of subwavelength metamaterials based on directly coupling resonating elements. In this case, when the holes coupling the boxes are small, we create networks of Helmholtz resonators with nearest-neighbour interactions. We use matched asymptotic expansions, in the small hole limit, to derive simple, yet asymptotically accurate, discrete wave equations governing the pressure field. These network equations readily furnish analytical dispersion relations for box arrays, slabs and crystals, that agree favourably with finiteelement simulations of the physical problem. Our results reveal that the entire acoustic branch is uniformly squeezed into a subwavelength regime; consequently, phononic box crystals exhibit nonlinear-dispersion effects (such as dynamic anisotropy) in a relatively wide band, as well as a high effective refractive index in the long-wavelength limit. We also study the sound field produced by sources placed within one of the boxes by comparing and contrasting monopole-with dipole-type forcing; for the former the pressure field is asymptotically enhanced whilst for the latter there is no asymptotic enhancement and the translation from the microscale to the discrete description entails evaluating singular limits, using a regularized and efficient scheme, of the Neumann's Green's function for a cube. We conclude with an example of using our asymptotic framework to calculate localized modes trapped within a defected box array.

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“…A number of researchers investigated the sound absorption performance of porous layers with embedded resonant inclusions [89][90][91][92][93][94][95][96]. Oliva and Hongisto [97] investigated and compared the accuracy of seven existing impedance prediction methods targeting the sound absorption coefficients of porous material.…”

Section: Porosity Materialsmentioning

confidence: 99%