## Introduction The invention of first-order Ambisonics (FOA) in the mid-1970s by Michael Gerzon and Peter Fellgett was following the classical coincident audio recording and playback principles from the 1930s. First-order Ambisonics is an extension of Blumlein's [[Stereophonic#ms_intensitybased|M-S recording system]]. ## History of first-order Ambisonics Felgett [1], Gerzon and Craven [2-4] were considered as the pioneers of the FOA technology. The scheme of M-S microphone system is extended to 3D first-order Ambisonics by a third figure-of-eight microphone of up-down aiming. [5] ### Gerzon's designing paper [2], March 1975 ### 2D FOA ### 3D FOA ## External resource - Ambisonic Net: [https://www.ambisonic.net/](https://www.ambisonic.net/) - Thornton, Stephen (14 May 2010). Michael Gerzon: Audio Pioneer 1945 – 1996: [https://www.michaelgerzonphotos.org.uk/](https://www.michaelgerzonphotos.org.uk/) - Visualization XY stereo microphone system Blumlein Pair Eight/Eight 90° Intensity Stereo: [https://sengpielaudio.com/Visualization-Blumlein-E.htm]( https://sengpielaudio.com/Visualization-Blumlein-E.htm) - Into the Soundfield: Michael Gerzon and Ambisonics at Oxford: [https://intothesoundfield.music.ox.ac.uk/](https://intothesoundfield.music.ox.ac.uk/) - ambiX v0.3.0: [https://www.matthiaskronlachner.com/](https://www.matthiaskronlachner.com/) - Ambisonics in the 21st Century: A Review of Spatial Audio Techniques - Michael Zeligs, CCRMA: [https://ccrma.stanford.edu/blogs/mzeligs/ambisonics-in-21st-century-review-of-spatial-audio-techniques](https://ccrma.stanford.edu/blogs/mzeligs/ambisonics-in-21st-century-review-of-spatial-audio-techniques) ## References [1] P. Felgett, Ambisonic reproduction of directionality in surround-sound systems. Nature 252, 534–538 (1974) [2] Gerzon, M.A. (1975). The Design of Precisely Coincident Microphone Arrays for Stereo and Surround Sound. _Journal of The Audio Engineering Society_. Download: [http://pcfarina.eng.unipr.it/Public/B-format/A2B-conversion/Gerzon/Design_Precisely_Coincident_Microphone_Arrays.pdf](http://pcfarina.eng.unipr.it/Public/B-format/A2B-conversion/Gerzon/Design_Precisely_Coincident_Microphone_Arrays.pdf) [3] P. Craven, M.A. Gerzon, Coincident microphone simulation covering three dimensional space and yielding various directional outputs, U.S. Patent, no. 4,042,779 (1977) [4] Gerzon, M.A. (1973). Periphony: With-Height Sound Reproduction. _Journal of The Audio Engineering Society, 21_, 2-10. [5] Zotter, Franz & Frank, Matthias. (2019). Ambisonics: A Practical 3D Audio Theory for Recording, Studio Production, Sound Reinforcement, and Virtual Reality. 10.1007/978-3-030-17207-7. Download: [https://link.springer.com/content/pdf/10.1007/978-3-030-17207-7.pdf](https://link.springer.com/content/pdf/10.1007/978-3-030-17207-7.pdf)