English: Map of a whispering gallery wave in an enclosed cylinder with of air of the same diameter as the whispering gallery at St Paul's Cathedral. Red and blue represent higher and lower air pressures, respectively, and the distortion in the grid lines represents the air particle displacements. The pitch of this wave is 69 Hz. Image created by the Applied Solid State Physics Laboratory, Division of Applied Physics, Faculty of Engineering, Hokkaido University Sapporo, Japan. Jan. 31, 2012