Hearing aid signal processing for a real-time auralization system
Master Thesis of Tumbrägel, Jonas
Signal processing algorithms for hearing aids have been extensively investigated and improved in the last decade and are usually adjusted under laboratory conditions. In real-world situations however, hearing aid users still report an unsatisfying sound perception, especially within noisy environments. In order to increase the performance of hearing aids in difficult everyday situations, hearing aids algorithms need to be evaluated in more realistic test scenarios in cooperation with HA users. Suitable test conditions in real-world environments cannot be created efficiently or lack in flexibility. Virtual acoustic environments (VAE) are used to simulate real-world acoustic scenes and to enable controlled listening conditions. To avoid inaccurate sound field reproduction for hearing aids in VAE, simulated signals can be processed with hearing aid algorithms and subsequently inserted to a dummy hearing aid (DHA). Hearing aid users with mild to moderate hearing loss do not only perceive the surrounding sound field amplified through the hearing aid, but still have remaining hearing capabilities which have to be addressed. This is done by expanding the system by a loudspeaker-based reproduction in combination with a crosstalk cancellation filter network. In this work, different hearing aid signal processing algorithms implemented on a Master Hearing Aid platform are investigated and evaluated. Additionally, measurements of the electroacoustic properties of a DHA have been carried out. Finally, these two system components have been integrated into the VAE and were tested in a combined evaluation.