1984 年 40 巻 2 号 p. 71-78
High-frequency acoustical fields excited in a concave rigid wall by a source located on the wall surface are described. Acoustical pressure fields can be expressed in alternative representations:(1) a combination of Whispering Gallery modes and continuous spectrum and (2) a combination of acoustical rays and Whispering Gallery modes. The analysis is performed by an asymptotic evaluation of the rigoriously formulated Green's function. Pressure fields are expressed in the 3-dimensional projection, as parameters of circumferential distance from the source and radial distance from the wall surface. Strong emphasis is placed on the physical interpretation of the results. Most pleasing from a physical standpoint is a fields solution that comprises a mixture of a few geometric acoustical rays and Whispering Gallery modes.