ESMA-3D Immersive Soundscape Recordings

ESMA3D (Equal Segment Microphone Array 3D) is a 3D mic array technique for 360° recording developed by Hyunkook Lee of the APL. It consists of 8 microphones arranged in a horizontally spaced, vertically coincident fashion. This provides a very good spaciousness and stable/accurate horizontal and vertical imaging as well as a realistic impression of being there and strong immersion. The main layer (mainly responsible for capture sound sources) is a 50cm x 50cm square of four cardioid microphones spaced with a 90° subtended angle between each pair of mics. The upper layer uses 4 supercardioid mics facing upwards for capturing ambience and elevated sources like birds. The lower and upper layers are coincident (0 spacing, but with a subtended angle of 90 to 120° to have enough level difference between the layers for stable vertical localisation). This design is based on our previous findings showing that vertical mic spacing has little or no contribution to spatial impression in 3D recording. The Schoeps ORTF3D is a brother/sister mic array sharing the same concept - horizontal spacing/vertical coincidence. The reproduction of ESMA3D requires the 8-channel Cube speaker array or 9.1 Dolby Atmos or Auro-3D setup (without the centre and sub), or it can be also binaurally or/and Ambisonically rendered, which still preserves a good quality if used with a good quality decoder, e.g. IEM plugin suite or Aalto SPARTA suite. More details about the array design and listening test results can be found in our AES papers below. http://www.aes.org/e-lib/browse.cfm?elib=19883 http://www.aes.org/e-lib/browse.cfm?elib=19401 http://www.aes.org/e-lib/browse.cfm?elib=17560 http://www.aes.org/e-lib/browse.cfm?elib=20392

ESMA3D（Equal Segment Microphone Array 3D，等分段麦克风阵列3D）是由APL的Hyunkook Lee开发的一款用于360°全景录音的三维麦克风阵列技术。该阵列由8个麦克风组成，采用水平等距排布、垂直共面的布局方式，可实现出色的空间感与稳定精准的水平、垂直声场成像，同时带来逼真的临场感与强烈的沉浸体验。
核心拾取层（主要负责拾取声源）为50cm×50cm的正方形排布结构，包含4个心形指向麦克风（cardioid microphone），每对麦克风之间的张角为90°。上层阵列采用4个超心形指向麦克风（supercardioid microphone），朝上朝向以拾取环境音与鸟类等高空声源。上下两层垂直共面（间距为0，但张角设置为90°至120°，以保证两层间具备足够的声级差，实现稳定的垂直声源定位）。该设计基于此前的研究结论：在三维录音中，麦克风的垂直间距对空间感的影响微乎其微，甚至无显著作用。
Schoeps ORTF3D是与其同源的麦克风阵列，采用相同的设计理念——水平间距排布、垂直共面布局。
ESMA3D的重放需搭配8通道立方体扬声器阵列，或9.1声道杜比全景声（Dolby Atmos）、Auro-3D声场系统（省略中置声道与低音声道）；也可通过双耳声渲染或/和环绕声编码技术（Ambisonics）进行重放，若搭配优质解码器（如IEM（入耳式监听，In-Ear Monitor）插件套件或Aalto SPARTA套件），仍可保证良好的音质表现。
更多关于该阵列设计与听感测试结果的细节，可参阅以下音频工程学会（Audio Engineering Society, AES）论文：
http://www.aes.org/e-lib/browse.cfm?elib=19883
http://www.aes.org/e-lib/browse.cfm?elib=19401
http://www.aes.org/e-lib/browse.cfm?elib=17560
http://www.aes.org/e-lib/browse.cfm?elib=20392