Signal processing methods to address some challenges in binaural hearing aids

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The proposal aims to achieve significant steps towards the following long-term objectives: 1) To increase performance and robustness of hearing aids and achieve greater acceptance and usage by people with hearing disability, and 2) to make hearing aids and, in general, multichannel speech/audio/acoustics processing systems robust to difficult, challenging real-life acoustic environments, including the presence of competing talkers, of various types and levels of noise, and reverberant conditions. To achieve progress towards these objectives, three short-term objectives are proposed.In binaural hearing aids (and other applications as well), there can be a mismatch or an error between the target direction of arrival assumed for processing and the actual target direction of arrival, because of imperfect direction of arrival estimation schemes, small head movements from the hearing aid user, and multipath propagation. This mismatch can result in significant performance degradation in beamforming algorithms, and it is still an important problem today. The first short-term objective of this proposal is to develop beamforming algorithms for binaural hearing aids which are robust to errors in the estimated target direction of arrival.The ear-to-ear communication through a wireless link is another challenge in binaural hearing aids, with challenging specifications for the audio coding including low bandwidth, low delay (less than 1-2 ms), low complexity, and wideband spectrum. The second short-term objective of the proposal consists of developing a sub-band domain backward linear prediction audio coding scheme for binaural hearing aids. We will add a new noise shaping scheme including real-time feedback from the white noise gain of the binaural beamforming algorithm, to avoid or reduce quantization noise amplification by the beamforming algorithm. Moreover, a custom packet loss concealment scheme will be developed for the low-delay sub-band codec, considering the specific low-delay constraint and coder-decoder synchronization issues of the backward linear prediction coding scheme being used.The third short-term objective concerns the further development of a scheme that we recently proposed for binaural hearing aids beamforming, which can both reduce noise and preserve the binaural cues of the background noise and competing talkers. We will investigate various strategies to reduce the complexity of the method by exploiting redundancies between components and by choosing components that allow better sharing of resources. We will also investigate the development of bandwidth efficient versions of the algorithms, where the number of signals that need to be transmitted through a wireless link is minimized. These improvements will significantly improve the battery life of hearing aids implementing the proposed method.