Dr. Martin Archer, space physicist at Queen Mary University of London, and lead author of the paper, said: "There had been speculation that these drum-like vibrations might not occur at all, given the lack of evidence over the 45 years since they were proposed. Another possibility was that they are outer boundary of Earth's magnetic field vibrates like a drum. Credit: Martin Archer, Queen Mary University of London"Earth's magnetic shield is continuously buffeted with turbulence so we thought that clear evidence for the proposed booming vibrations might require a single sharp hit from an impulse.