Acoustic focusing using beamforming for augmented sensing

Abstract

Selective listening is a key feature of the human auditory system. It is the ability to selectively listen to one specific talker or voice in presence of multiple talkers, voices and/or background noise. The auditory system does this by using complex binaural signal processing that can exploit directional, spectral and visual cues. The task of selective listening in such complex sound environments has been termed the "cocktail party problem". Studies have shown that listeners with sensorineural hearing loss experience greater difficulty in these situations. Much attention has been given to this issue by research institutions and hearing aid manufacturers. Recently, different solutions based on the use of microphone array beamforming have been proposed. These solutions can generally be divided into fixed beamforming or adaptive beamforming systems. Fixed beamforming systems do not depend on the input, whereas adaptive beamforming systems can adapt their directional properties depending on the sound field. Adaptive systems can potentially achieve greater performance in certain situations, but fixed beamforming systems are generally said to be more robust and versatile. In this thesis, a solution to the cocktail party problem based on fixed beamforming for a microphone array will be described. A special trait of the solution proposed is the focus on obtaining a frequency invariant response. Frequency invariant beamforming avoids a coloration of the sound that most conventional methods do not. Yet, existing research on the subject has been found to be very limited. To investigate the performance of the proposed method, simulations and measurements have been conducted. Ideally, subjective testing should be performed to test the speech intelligibility of subjects using the proposed system method to other available methods. Unfortunately, such a test is very extensive and beyond the scope of this thesis. Lastly, interesting topics worthy of further research will be discussed.