Acoustically transparent sound presentation in hearing devices: Algorithms,devices and models
Henning SCHEPKER(1,4) , Florian DENK(2,4) , Reinhild RODEN(3) , Matthias BLAU(3,4) , Birger KOLLMEIER(2,4) , SimonDOCLO(1,4)(1) Signal Processing Group, Dept. of Medical Physics and Acoustics, University of Oldenburg, Germany(2) Medizinische Physik, Dept. of Medical Physics and Acoustics, University of Oldenburg, Germany(3) Institut für Hörtechnik und Audiologie, Jade Hochschule Oldenburg, Germany(4) Cluster of Excellence Hearing4all, Germany

Abstract
Assistive hearing devices often have a low user acceptance due to a limited sound quality. Recently, the conceptof acoustic transparency was proposed to increase the sound quality for hearing-impaired and normal-hearing
users. Acoustic transparency of a hearing device refers to the acoustic perception of an open ear canal while
the device is inserted in the ear. This can be achieved by applying an equalization filter to the output of thedevice such that the transmission properties of the open ear are obtained [1, 2]. In this contribution we givean overview of our approach to acoustically transparent sound presentation. We present recent advances in ourcustom earpiece design with multiple receivers and microphones [1, 3] as well as signal processing algorithms
for robust acoustic feedback suppression [4] and sound pressure equalization [1, 4, 5, 6]. We present resultsfrom subjective evaluations of a real-time demonstrator in terms of the overall quality compared to the openear [7] and outline future research directions, e.g., using individualized electro-acoustic models to alleviate thenecessity of measuring the acoustic transfer functions within the device and to the eardrum [8].
Keywords: Acoustic Transparency, Feedback Cancellation, Sound Pressure Equalization

ACKNOWLEDGEMENTS
Funded by the Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 352015383 – SFB 1330 A4 and C1,
as well as Projektnummer 390895286 – EXC 2177/1.

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