Normal Mode Interpretation of the Sound Propagation in Whispering Galleries

Abstract

THE propagation of sound in ‘whispering galleries’¹ is a very remarkable phenomenon, and in Lord Rayleigh's Theory of Sound he gives his well-known interpretation based on observations at St. Paul's Cathedral in London. According to my observation, which agrees with Lord Rayleigh's comment in his book, the opinion of the Astronomer Royal ascribing the phenomenon to the reflexion at the upper dome is hard to accept. This follows because at the diametrically opposite point of the gallery the whisper can scarcely be heard, whereas it becomes stronger as one approaches the speaker.