In this paper, the numerical solution of the
statistical chains of matrix B is successfully used to
calculate the sound intensity field in audio rooms.
Here we use B-chain techniques as a real
breakthrough with the time-dependent sound field
problem in 3D geometric space. We offer the appropriate
design of audio rooms via an example of a cuboid pieces.
We also show that B-chain techniques can produce
rigorous statistical proof of Sabines' imperial formula for
reverberation time in audio rooms.
In addition, the definition of so-called statistical
weights of geometric shapes is introduced and found to be
effective in solving double and triple integration as well as
sound diffusion transfer equation in audio rooms.