Current hearing systems perform desired modification of sound (such as amplification in hearing aids), but also introduce undesired distortions. This makes many devices sound unnatural and decreases the audio quality, which is one of the reasons for low acceptance of hearing systems, particularly among potential first-time users.

To overcome this issue, the aim of this work package is to develop an acoutsically transparent hearing system - that is a device that occludes the ear and includes all component of a full hearing aid, but can be operated in a basis mode where the overall transfer characteristics to the eardrum are comparable to an open ear. The subjective listening impressionis supposed to be alike to the open ear, and the device becomes transparent with respect to the listener's perception.

As a common research platform, an earpiece prototype containing 3 microphones and 2 loudspeakers in each ear has been developed. the electronics can be included in individual earmoulds or generic earplugs.

Using an custom in-situ calibration routine, the electro-acoustic transfer path is individually adjusted to each user such that in superposition with the direct sound leaking through the vent a frequency response that is comparable to the open ear is achieved. Scientific studies showed that in this setting it is hard for subjects to distinguish between listening through a simulated open ear and a presentation through the device. Also, the audio quality of this device was shown to be significantly better than with a standard behind-the-ear hearing aid.

Current research activities include

·  Modelling the electro-acoustic system for better sound field control and feedback cancellation optimally exploiting the special layout.

·  Sound transmission to the ear in contect with this hardware layout

·  Adaptive sound equalization equalization and integration with hearing aid algorithms

·  Integration of a brain-computer interface into the device

Investigators:
Florian Denk Birger Kollmeier
Cooperation with TPF: Matthias Blau, Steffen Vogl.

Publications

Denk, F., Hiipakka, M., Kollmeier, B., Ernst, SMA. (2017) An Individualised Acoustically Transparent Earpiece for Hearing Devices, International Journal of Audiology (Early Online).
Limited free donwload is available here.

Denk, F., Kollmeier, B., Ernst, SMA. (2016). High-Fidelity Hearing Instruments: Evaluating Listening Quality of a new Prototype using a Method for Evaluating Modified Listening (MEML). Audio Engineering Society Conference on Headphone Technology, Aalborg