On in situ beamforming in an automotive cabin using a planar loudspeaker array
* Presenting author
Compact loudspeaker arrays are often used in applications where control of the sound dispersion is required, e.g. in audio reproduction systems and aspects of sound field control. An example of the latter is sound zoning where the goal is to deliver individual audio content to one listener without disturbing another. Typical approaches are based on filter-and-sum beamforming applied to control the resulting directivity of the array. However, directivity is defined in free field while sound zones are generally of interest in listening spaces with reflective boundaries such as domestic rooms and automotive cabins. In order to address this discrepancy, in situ zone control can be utilized. This relies on measured transfer functions from each array element to the spatial control points defining the zones. Such methods increase the solution specificity and can lead to non-causal control filters. In the present paper, methods based on controlling the flow of acoustic energy are applied to a planar loudspeaker array located on the dashboard inside a car cabin. A comparison study including directivity and in situ zone control is presented, and the solutions are evaluated in terms of spatial robustness of the resulting sound zoning performance.