Project C1 - MIMO acoustic earpiece for combined equalization, feedback cancellation and noise reduction
The long-term goal of this project is to achieve acoustically transparent speech communication and hearing support by means of a multi-input multi-output (MIMO) earpiece with integrated microphones and receivers (Denk et al., 2017, 2018). The main research question is how to optimally exploit the availability of multiple microphones and receivers in the ear canal and vent to develop combined solutions for sound pressure equalization at the ear drum, for acoustic feedback cancellation, for (active) noise reduction and for occlusion control.
To this end, novel signal processing algorithms as well as electro-acoustic models will be developed that enable to individualize these solutions for each user and take into account the interaction effects between the different objectives.
Figure 1: MIMO earpiece prototype with multiple integrated receivers and microphones (Denk et al., 2017, 2018). Two microphones are located in the so-called core, with one microphone at the inner face pointing towards the eardrum and one microphone at the outer face pointing outwards, whereas the third microphone is located in the concha. Two receivers are located next to the microphones in the core.
This project is based on results obtained in the DFG Research Unit FOR1732 “Individualized Hearing Acoustics”, where different methods for sound pressure equalization and feedback cancellation have been developed and validated (Sankowsky-Rothe et al., 2015; Denk et al., 2017, 2018; Schepker et al., 2017a,b). More specifically, in this project combined solutions for sound pressure equalization, acoustic feedback cancellation and (active) noise reduction will be developed. In addition, active occlusion control will be investigated to counteract the unnatural perception of the own voice that may occur when combining different algorithms. In order to understand the behavior of the considered MIMO earpiece to variations of electro-acoustic components and the individual ear canal, an electro-acoustic model will be developed.
The results of this project will contribute to the development of the demonstrators “System technology for hearing aids I: The acoustically transparent hearing device” and “System technology for hearing aids II: The immersive hearing device”.
Figure 2: Block diagram depicting multi-receiver-multi-microphone signal processing for combined acoustic feedback cancellation and sound pressure equalization and electro-acoustic modeling of the MIMO earpiece (Denk et al., 2017).