Higher-order Ambisonics
A particularly active area of current research is the development of "higher orders" of Ambisonics. These use more channels than the original first-order B-Format to capture significantly more spatial information. At present, "real" recording techniques using them are in their infancy, it is, however, straightforward to compose synthetic recordings. Benefits include greater localisation accuracy and better performance in large-scale replay environments such as performance spaces.
The higher orders correspond to further terms of the multipole expansion of a function on the sphere in terms of spherical harmonics. As discussed at wave field synthesis, in the absence of obstacles, sound in a space over time can be described as the pressure at a plane or over a sphere – and thus if one reproduces this function, one can reproduce the sound of a microphone at any point in the space pointing in any direction.
Read more about this topic: Ambisonics, Current Developments