  We study the solutions of the wave equation where a massless scalar field is
coupled to the Wahlquist metric, a type-D solution. We first take the full
metric, and then write simplifications of the metric by taking some of the
constants in the metric null. When we do not equate any of the arbitrary
constants in the metric to zero, we find the solution is given in terms of the
general Heun function, apart from some simple functions multiplying this
solution. This is also true, if we equate one of the constants $Q_0$ or $a_1$
to zero. When both the NUT related constant $a_1$ and $Q_0$ are zero, the
singly confluent Heun function is the solution. When we also equate the
constant $\nu_0$ to zero, we get the double confluent Heun-type solution. In
the latter two cases, we have an exponential and two monomials raised to powers
multiplying the Heun type function. Thus, we generalize the Batic et al. result
that the solutions of the Teukolsky equations for type-D metrics give Heun type
solutions.
