Although 2.5D sound field synthesis with a circular loudspeaker array can be used in a 3D sound field, a 2D sound field, instead of a 3D sound field, is assumed for a sound field recording with a circular microphone array. This paper presents a horizontal 3D sound field recording and 2.5D synthesis method used in 3D sound fields with multiple co-centered omni-directional circular microphone arrays and a circular loudspeaker array without vertical derivative measurements. The spherical harmonic spectrums used for 2.5D synthesis are extracted from the recorded horizontal sound pressures and the driving function of a circular sound source is analytically derived based on 2.5D higher-order Ambisonics. The results of computer simulations indicate the effectiveness of the proposed method, in comparison with the conventional least squares-based pressure matching, and 2D cylindrical harmonic analysis-based approaches.

https://ieeexplore.ieee.org/document/8683009/