Design of a broadside array for a binaural hearing aid

This paper describes the design and implementation of a binaural directional hearing aid. This hearing aid consists of a microphone array of five directional microphones integrated into the front of a pair of spectacles. The signals of the microphones are processed with the aid of double beamforming into a left-ear and a right-ear signal. The directivity pattern of the left-ear signal has its main lobe at a small angle to the left, and the directivity pattern of the right-ear signal at a small angle to the right. These different main lobes cause an interaural level difference (ILD). In natural conditions, an ILD enables the human auditory brain to localize sound sources and to significantly improve speech intelligibility in noise. A computer simulation and an implementation in analogue electronics show that the main lobes for the left-ear and right-ear realize sufficient ILD at high frequencies to enable an effective localization of sound sources.