Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An acoustic metamaterial lens for acoustic point-to-point communication
  in air   Acoustic metamaterials have become a novel and effective way to control sound
waves and design acoustic devices. In this study, we design a 3D acoustic
metamaterial lens (AML) to achieve point-to-point acoustic communication in
air: any acoustic source (i.e. a speaker) in air enclosed by such an AML can
produce an acoustic image where the acoustic wave is focused (i.e. the field
intensity is at a maximum, and the listener can receive the information), while
the acoustic field at other spatial positions is low enough that listeners can
hear almost nothing. Unlike a conventional elliptical reflective mirror, the
acoustic source can be moved around inside our proposed AML. Numerical
simulations are given to verify the performance of the proposed AML.

27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex