  In this work, a novel analysis of a hybrid discontinuous Galerkin method for
the Helmholtz equation is presented. It uses wavenumber, mesh size and
polynomial degree independent stabilisation parameters leading to impedance
traces between elements. With analysis techniques based on projection operators
unique discrete solvability without a resolution condition and optimal
convergence rates with respect to the mesh size are proven. The considered
method is tailored towards enabling static condensation and the usage of
iterative solvers.
