  The question of whether there exists an approximation procedure to compute
the resonances of any Helmholtz resonator, regardless of its particular shape,
is addressed. A positive answer is given, and it is shown that all that one has
to assume is that the resonator chamber is bounded and that its boundary is
$\mathcal C^2$. The proof is constructive, providing a universal algorithm
which only needs to access the values of the characteristic function of the
chamber at any requested point.
