说明：  二维声子晶体FDTD方法计算禁带宽度的例子,FIR 底通和带通滤波器和IIR 底通和带通滤波器，实现了对10个数字音的识别。
( Dimensional phononic crystals FDTD method calculation examples band gap, Bottom-pass and band-pass FIR and IIR filter bottom pass and band-pass filter, To achieve the recognition of 10 digital sound.)