They used a concave disk-like speaker to produce sound. This solid shape makes the sound waves kind of spin around themselves like a tornado or one of those bub

They used a concave disk-like speaker to produce sound. This solid shape makes the sound waves kind of spin around themselves like a tornado or one of those bubble rings you see people blow underwater [1] instead of a normal pressure wave that goes in all directions. The tornado sound wave can only move forward and once it hits something is dissipated and doesn't reflect the sound. 1. https://youtu.be/t2kvEC852MI?si=QJjinL7AK6ZZS_SO https://youtu.be/t2kvEC852MI?si=QJjinL7AK6ZZS_SO