Section B - Algorithms
In current hearing device technology, the largest speech communication benefit in adverse listening conditions is typically achieved by directional filters. However, to utilize this benefit, hearing aid users may need to change their natural head motion behavior and loose the sense of immersion in the sound environment.
The long-term goal of this project is to achieve a breakthrough in the theoretical foundation and realization of auditory-inspired algorithms for analysing and processing speech in complex acoustic conditions, in order to fundamentally improve speech communication in these conditions for people with hearing difficulties.
At the core of this project is the CRC’s acoustic communication loop, implemented as a hierarchy of consecutive processing layers, in which the sound field is transformed into an increasingly abstract and invariant („high-level“) representation. Subsequent to an active listening decision at the top-level, the counterpart to the subject's percept, the hierarchy is traversed in reverse („top-down“) direction.
A sound arriving from a certain direction in space (e.g., off the midline) arrives at the two ears at slightly different times. This is called the interaural time difference (ITD). In addition, the head attenuates the sound at the ear opposite of the sound source resulting in an interaural level difference (ILD). Due to the complex interplay of changing interaural cues caused, e.g., by head movement on the one hand, and by auditory processing on the other hand, models are inevitable in this branch of auditory research, to be able to understand the system behavior.