1. An apparatus, comprising: a case defining a plurality of openings in an external surface of the case; and a plurality of microphones fastened to the case, wherein each microphone in the plurality of microphones is located adjacent to a respective opening in the plurality of openings, wherein the external surface of the case at least partially defines a plurality of funnel-shaped surfaces configured to cause direction-dependent variations in spectral notches and frequency response of received audio, each of the funnel-shaped surfaces in the plurality of funnel-shaped surfaces has a respective inlet and a respective outlet, and a respective diaphragm of each microphone in the plurality of microphones is located adjacent to the respective outlet of a corresponding funnel.