In this article, the authors give a lower bound on the number of sign changes
of Fourier coefficients of a non-zero degree two Siegel cusp form of even
integral weight on a Hecke congruence subgroup. They also provide an explicit
upper bound for the first sign change of Fourier coefficients of such Siegel
cusp forms. Explicit upper bound on the first sign change of Fourier
coefficients of a non-zero Siegel cusp form of even integral weight on the
Siegel modular group for arbitrary genus were dealt in an earlier work of
Choie, the first author and Kohnen.Comment: minor typos fixe
