Japan’s Shinkansen bullet trains travel at speeds exceeding 300 km/h, pushing the limits of rail engineering. But early high-speed models faced an unexpected problem: when trains exited tunnels, they created powerful air pressure waves that sounded like miniature sonic booms—disturbing nearby communities. As a train speeds through a tunnel, it compresses air in front of it like a piston. When that compressed air suddenly escapes at the tunnel exit, it can produce a loud pressure blast. The faste