Directionalizing adaptive multi-microphone arrays for hearing aids using cardioid microphones

The authors examine the design and performance of a restricted geometry, adaptive four-element acoustic array using cardioid (directional) microphones for hearing enhancement. The array is portable and lightweight. It allows the hearing aid wearer to focus better in a forward-looking direction, reducing interfering noises from unwanted directions. The array also allows the system to respond to changing environments, nulling strong interference noises which do not impinge on the front of the array. The directionality and the adaptable interference rejection of the multi-element array are superior to that possible using single or two-element devices. Adaptive arrays using directional microphones are shown to enhance the array output SNR above that of an adaptive array consisting of omni-directional sensors. Examples and simulation results are presented.<>