Smart hearing aids that adapt to the individual needs of the user: The researchers at the Collaborative Research Center (CRC) Hearing Acoustics have been working on this for the past four years. Now the German Research Foundation (DFG) has extended the funding of the project. Led by Prof. Dr. Volker Hohmann, hearing researcher at the University of Oldenburg, the CRC will receive up to 8.1 million euros for a second phase of funding that runs from 2022 to 2026. Officially titled “Hearing Acoustics: Perceptual Principles, Algorithms and Applications” (HAPPAA), the CRC focuses on the development of hearing aids and hearing aid systems that use artificial intelligence (AI) to automatically adapt to different environments, allowing these devices to better adapt to the specific needs of individual users.
In addition to the University of Oldenburg, the Jade University of Applied Sciences, the Fraunhofer Institute for Digital Media Technology IDMT, the Hörzentrum Oldenburg gGmbH, the RWTH Aachen University and the Technical University of Munich – all leading institutions in the field of hearing research – are involved in this large-scale project that will last a total of twelve years.
In our aging society, it is becoming increasingly urgent to develop hearing aids and other communication aids that work effectively in difficult acoustic environments and really help people in everyday life. The Oldenburg hearing test does an excellent job and is highly regarded both nationally and internationally. The renewed funding commitment from the German Research Foundation underlines this impressively.”
Prof. dr. dr. Ralph Bruder, president, University of Oldenburg
When people interact with their acoustic environment
The Collaborative Research Center Hearing Acoustics brings together different disciplines, notably acoustics, psychoacoustics, audiology, engineering sciences and physical modelling. In the first funding period, the focus was on the interactions between hearing impaired people and their acoustic environment. “In real life, the hearing situation is constantly changing as people react to voices and sounds. For example, they turn their heads towards the sound source, or shift their gaze in that direction. We call this the ‘acoustic communication loop’,” says Hohmann. This dynamic loop had received little attention in hearing acoustics in the past, he notes.
In recent years, the team has succeeded in integrating the hearing aid into this acoustic communication loop. “We have developed a first prototype of the so-called ‘immersive hearing aid’ that constantly assesses the acoustic situation and identifies which sound source a test person focuses on at a given moment,” explains Hohmann. The device determines the direction of the test taker’s gaze and head movements and then adjusts signal processing to ensure that the intended sound source can be optimally heard by the test person. The current prototype can be used in field experiments as well as in the lab.
Among other factors, new perception models developed by the research team for use in various hearing situations have paved the way for this success. “These models predict how a test person perceives a sound signal in a certain situation, for example whether he can follow a conversation in a noisy environment or not,” explains Hohmann. Simulating hearing with and without hearing impairment in different hearing situations with background noise and reverberation is essential for the development and evaluation of innovative methods for signal processing in hearing aids, he emphasizes.
Test algorithms directly in the ear
Another important achievement from the first grant period is the “hearing aid” – a special, particularly high-quality ear piece for research purposes. The device, placed in the ear and equipped with several integrated microphones and small speakers, can amplify sound in exactly the same way as a hearing aid. The researchers can use it to test new signal processing algorithms directly in the ear, for example. The special thing about this is that the hearing aid is acoustically transparent – which means that hearing with this device corresponds to normal hearing with an open ear. “Thanks to the interdisciplinary collaboration within the CRC, we have been able to combine acoustics and signal processing methods and have made significant progress,” says Hohmann.
The team has also developed an interactive, audiovisual virtual reality set-up in the lab to conduct hearing experiments with test subjects under controlled conditions. With this technology, real-life situations can be simulated more realistically than was previously possible. To do this, the team created several complex audiovisual scenarios in which test subjects can ‘immerse’ themselves, including a virtual restaurant, a metro station and a living room. These scenarios, along with the related data, have been made freely available to research labs around the world so that they can conduct their own hearing experiments.
Active Noise Canceling
In the second funding period now underway, the CRC team plans to refine and merge its perception models, algorithms and applications. One of the goals is to develop hearing aid and immersive hearing aid algorithms that can actively control sound depending on the acoustic scenario. For this, the researchers use advanced AI methods that they have developed themselves. The long-term goal is for each hearing aid to constantly learn and better predict which setting is optimal for the particular user in a specific situation. Hearing impaired people must be able to enter the necessary feedback themselves via their smartphone. “However, there is still a lot of work to be done before we reach this goal,” notes Hohmann.
The team is also working to establish international standards for complex acoustic scenarios in hearing research and audiology to facilitate and improve exchanges between different laboratories. In addition, the CRC wants to develop new hearing-acoustic tests in virtual environments that will allow researchers to better identify differences in individual perception. This should make it possible to design diagnostics and hearing aid rehabilitation measures that are optimally tailored to individual needs.
The Collaborative Research Center complements research from the Cluster of Excellence Hearing4all, which is also led by researchers from the University of Oldenburg. In addition, it actively supports early scientists’ doctoral projects with its own integrated Research Training Group.
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