Hearing technology in biomedical engineering
Audiological and Medical Acoustics
According to the World Health Organisation, over 5 % of the world population suffer from disabling hearing loss. Although most of these individuals are provided with rehabilitative interventions such as hearing aids, communication in everyday life is still tremendously more difficult in comparison to normal-hearing individuals. This becomes evident particularly in complex acoustic situations such as noisy restaurants, classrooms or during outdoor activities in urban environments. Current clinical practices, however, do not provide effective ways to diagnose hearing loss or verify hearing aid fittings by other means than oversimplified laboratory scenarios, which are not comparable to real-world listening scenarios with multiple stationary or moving sound sources and sometimes adverse room acoustics. While hearing aid fitting and other auditory rehabilitative procedures should still remain in a controlled clinical or laboratory setting, providing adequate logistics and healthcare conditions, application of virtual acoustic technology potentially increases their effectivity by integrating simulated complex acoustic environments including plausible room acoustics. Using this technology, the hearing aid candidate is tested and fitted under more plausible conditions in the clinic, thus potentially decreasing the gap between laboratory and real-world listening conditions to increase the hearing aid user’s satisfaction.
We are currently working on new testing paradigms and tools with the aim to improve diagnosis, treatment and auditory training for people with hearing loss.
Ear couplers for children
For the fitting and development of hearing aids for adults only very few standardized couplers or ear simulators exist which imitate the ear canal with its acoustic properties and so allow an optimal adjustment of the hearing aid.
For children and infants such couplers and measuring devices do not exist or are not standardized. The narrower auditory canal in children results in enormous differences with regard to the acoustic properties compared to adults. The fitting of a hearing aid for infants using the measuring techniques for adults can easily lead to a mismatch of 20 dB (SPL).
We examine children's ear canals and point out the differences to adults. Methodologically this is done with acoustic measuring as well as simulations (FEM). For simulations we revert back to geometric data from CT-scans and model the auditory canals.
Spatial Perception in Imaging MethodsCopyright: Uniklinikum Aachen, ITA
The systematic continuous development of reproduction methods of spatial acoustic scenarios are a focus of our research. Different methods have helped to achieve considerable progress particularly with regard to individually adapted stimulation, especially with regard to binaural reproduction (with headphones and loudspeakers). The basis for this is on the one hand the person-related measurement the so-called head-related-transfer-function (HRTF) (see Research Area\Binaural Technology) and adapted to this on the other hand a systematic distortion correction of the headphones applied.
The functional imaging in psychiatry, psychotherapy and psychosomatics attempts to continue to develop the established paradigms and to arrange them increasingly closer to reality. Whilst major progress has been made during the last decade in the optical and olfactory presentation of stimuli, the opportunities for acoustic stimulation continue to be clearly limited due to the headphone systems applied.
In this interdisciplinary research area we are investigating in close cooperation with JARA-BRAIN and the Forschungszentrum Jülich GmbH (Institut für Neurowissenschaften und Medizin, (Institute for Neuroscience and Medicine) Structural and functional Organization of the Brain (INM -1)) the systematic evaluation of the capacities of the existing systems for acoustic stimulation, their optimization and the identification of systematic weaknesses respectively in order to identify starting points for new developments.
We are researching in what quality acoustic stimulation for spatial perception in visualization processes can be conducted.