The design of improved first order ambisonic decoders by the application of range removal and importance in a heuristic search algorithm

This paper presents improvements to previous work on deriving first order Ambisonic decoders for ITU 5.1. The decoders are derived using a heuristic search method with an objective function based upon Gerzon’s metatheory of auditory localisation. An analysis of previously derived decoders shows that they are biased towards particular design objectives due to the nature of the multiobjective function guiding the search. This paper applies a technique called range removal to systematically and logically remove this bias which leads to improved decoder coefficients that better meet all of the objectives. A further technique known as importance is introduced that enables the logical biasing of range-removed objectives. A case study to develop a “max rE” decoder demonstrates this technique in action.