(Michael Gerzon’s Movie here)

First-order Ambisonic is an expansion of the MS format. It includes the horizontal plane. For 2D recordings, we saw that a Double-MS microphone arrangement can encode the signal in the frontal and median planes.

To record in 2D First-Order Ambisonic format we can use a Double-MS arrangement as shown in the previous section. It is possible to add another figure-of-8 microphone and create a Triple-MS array to record channels W,X,Y,Z/. Using the same principle, a coincident tetrahedron microphone array of cardioids with aiming directions FLU-FRD-BLD-BRU works given:

FLU = Front Left up FRD = Front Right Down BLD = Back Left Down BRU = Back Right up

which gives the matrix:

$$g(\theta )=\frac{1}{2}+\frac{1}{2}\left[\begin{array}{c}\hfill {\theta}_{FLU}^{T}\hfill \\ \hfill {\theta}_{FRD}^{T}\hfill \\ \hfill {\theta}_{BLD}^{T}\hfill \\ \hfill {\theta}_{BRU}^{T}\hfill \end{array}\right]\theta =\frac{1}{2}+\frac{1}{2}\frac{1}{\sqrt{3}}\left[\begin{array}{ccc}\hfill 1\hfill & \hfill 1\hfill & \hfill 1\hfill \\ \hfill 1\hfill & \hfill -1\hfill & \hfill -1\hfill \\ \hfill -1\hfill & \hfill 1\hfill & \hfill -1\hfill \\ \hfill -1\hfill & \hfill -1\hfill & \hfill 1\hfill \end{array}\right]\theta $$ |