Rayleigh scattering of spherical sound waves

This paper considers diffraction of spherical waves on soft, hard, and impedance spheres. Radius of the sphere is assumed to be small compared to acoustic wavelength. Simple uniform asymptotic expansions are obtained, which describe the scattered wave everywhere outside the scatterer, including a transition from the near to the far field. The new asymptotic expansions admit an intuitive interpretation in terms of image sources and reduce to the classical results due to Kelvin and Rayleigh in appropriate limiting cases.