２５坪普羅住宅的音響室夢想

[jimmywu]

Generally, the governing equation for acoustic propagation is the Helmholtz equation and it can be solved by boundary element method (a simplified FEM). I wrote my own program and published a paper on the 3-D scattering of ultrasonic waves by red blood cell. it really takes time. In FEM, we solve more complicated Navier-Stoke equations. Whatever, 反射/透射/吸收的各種參數 is the key for solving acoustic problem by BEM (FEM too). For smooth concrete wall, total reflection may be a good assumption. Or try to get the data of acoustic impedance (density times sound speed), you can also get a precise boundary condition. For materials other than that, such as rough surface or absorptive material, measurements has to be made to estimate the above properties. The graphs look reasonable. How did you define the source? In acoustics, we usually make it a "Baffle" piston --- non-reflective plane source. Also, the grid size has to be smaller than 1/6 of the wave length, it seems to be a lesser problem at low frequency.