The Green function for the Neumann boundary value problem at the semiinfinite cylinder and the flat infinite baffle

This paper presents the Green function for the Neumann boundary value problem at the
rigid semiinfinite cylinder and the flat rigid infinite baffle. The function has been expressed as
the combination of the Hankel functions of the first and second kinds, and their derivatives –
all $n$-th order. The acoustic pressure has been presented in the two cases: the time harmonic
vibrations of a sector cylinder piston located on the semiinfinite cylinder, and the annular
sector piston located on the flat baffle in the vicinity of the semiinfinite cylinder.