Intersection numbers for normal functions

We expand the notion of a normal function for a Hodge class on an even-dimensional complex projective manifold to the notion of a 'topological normal function' associated to any primitive integral cohomology class. The definition of the intersection number of two topological normal functions is the analogue of that given by Griffiths and Green for classical normal functions. We give a simple proof that the intersection number of the normal functions is the same as the intersection number of their corresponding cohomology classes.