3.2. Acoustic Performance of the LAM. Then the finiteelement method (FEM) is used to study the acousticperformance of the LAM. Building a precise model is difficultbecause of the random distribution of micro/nanostructureson the lotus leaf. Alternatively, it can be simplified by anequivalent model (Figure 1h) based on the facts that, (1) thesize of micro/nanostructures is much smaller than theoperating wavelength of sound, (2) the micro/nanostructuresonly take up a small volume fraction in the air layer (