From the Journal of Acoustical Society of America <a href="https://pubs.aip.org/asa/jasa/article/157/4/2802/3344072/Focality-of-sound-source-placement-by-higher-ninth" rel="nofollow">https://pubs.aip.org/asa/jasa/article/157/4/2802/3344072/Foc...</a>