  We consider general perturbations of a Schwarzschild black holes in the
context of f(R) gravity. A reduced set of frame independent master variables
are determined, which obey two closed wave equations - one for the transverse,
trace-free (tensor) perturbations and the other for the additional scalar
degree of freedom which characterise fourth-order theories of gravity. We show
that for the tensor modes, the underlying dynamics in f(R) gravity is governed
by a modified Regge-Wheeler tensor which obeys the same Regge-Wheeler equation
as in General Relativity. We find that the possible sources of scalar
quasinormal modes that follow from scalar perturbations for the lower
multipoles result from primordial black holes, while higher mass, stellar black
holes are associated with extremely high multipoles, which can only be produced
in the first stage of black hole formation. Since scalar quasi-normal modes are
short ranged, this scenario makes their detection beyond the range of current
experiments.
