Narrowband Adaptive Acoustic Arrays For Directional Interference Nulling

Extended Summary We consider the design and performance of a restricted geometry, narrowband, adaptive 2-element (termed "small") acoustic array as used for directional hearing enhancement. An array is designed to be mobile and burden-free, so that the wearer is not encumbered by the harldware, while remaining usehl in noisy environments. The directionality of multi-element arrays, and thus the capability for interference rejection, is greatly superior to that possible with a single-element device. Enhanced directionality comes from the extra knowledge gained when acoustic signals are spatially sampled. Intuitively, we expect such a result since humans have 2 ears to hear with, and we do not have the "extra" one merely for redundancy. This increased knowledge comes at the expense of increased hardware requirements, as well as an increase in real-time computations and communications. We explore the balance between directionality improvlement and hardware requirements. Making the array adaptive is shown to enhance the array directionality above that achievable by a iixed array which we have examined previously. We examine the perf'ornnance of small, adaptive, nonlinear acoustic arrays for