Hearing assistance system | EPFL Graph Search

There is provided a hearing assistance system, comprising a transmission unit (10) comprising a microphone arrangement (17) for capturing audio signals from a voice of a speaker ( 11 ) using the transmission unit and being adapted to transmit the audio signals as radio frequency (RF) signal via a wireless RF link (12); a left ear hearing device (16B) and a right ear hearing device (16A), each hearing device being adapted to stimulate the user's hearing and to receive an RF signal from the transmission unit via the wireless RF link and comprising a microphone arrangement (62) for capturing audio signals from ambient sound; the hearing devices being adapted to communicate with each other via a binaural link (15) and to estimate the angular location of the transmission unit by exchanging data concerning the received RF signal level, the level of the audio signal captured by the microphone arrangement of the hearing devices, and the phase difference between the audio signal received via the RF link from the transmission unit and the audio signal captured by the microphone arrangement of the hearing device, wherein each hearing device is adapted to process the au dio signal received from the transmission unit via the wireless link in a manner so as to create a hearing perception, when stimulating the user's hearing according to the processed audio signals, wherein the angular localization impression of the audio signals from the transmission unit corresponds to the estimated azimuthal angular location of the transmission unit.

Experimental evaluation of speech enhancement methods in remote microphone systems for hearing aids

Gilles André Courtois, Vincent Pierre Olivier Grimaldi, Hervé Lissek

Enhancing speech intelligibility for hearing-impaired subjects in complex acoustic conditions is still a challenging topic of research. To mitigate the detrimental effects of background noise and reverberation, current hearing instruments incorporate various hardware and software strategies, among which speech enhancement algorithms are of primary importance. In this paper, two algorithms based on the multichannel Wiener filter (previously reported in the literature) and one proprietary algorithm are experimentally assessed and compared. All of them make use of a remote microphone worn by the speaker of interest. The objective of these algorithms is to improve the speech contribution within the hearing aid microphone signals. The algorithms are assessed in terms of interference reduction performance, speech quality, spatial hearing preservation, and technical requirements. Using a recorded database of audio signals, the effects of the signal-to-noise ratio and of the delay between the remote and hearing aid microphone signals are studied. The results show that the proprietary algorithm provides a good performance and yields the lowest distortion of the binaural localization cues, while being the most efficient in terms of computational cost and wireless usage. The main drawback is the degradation of the output sound quality that is observed when the remote and hearing aid microphone signals are not temporally aligned.

European Acoustics Association2018

Active Control mitigating the Ear Canal Occlusion Effect caused by Hearing Aids

Thomas Stefan Zurbrügg

The World Health Organization (WHO) estimates the prevalence of a disabling hearing loss to be above 5% world-wide 1. A treatment with a hearing aid - be it behind-the-ear (BTE), in-the-ear (ITE) or receiver-in-canal (RIC) - involves some degree of occlusion of the external ear canal. In many cases, this so-called occlusion effect (OE) leads to an unfamiliar perception of the hearing aid user’s own voice. This fact represents a limiting factor regarding the acceptance of hearing aids by potential users. This thesis focuses on modeling the physical occlusion effect caused by hearing aids and the investigation of active control approaches mitigating this adverse effect. A simple model based on audiological transfer functions is presented, discussed and validated in the first part of the thesis. This model is subsequently used as a basis for the analysis and the synthesis of an active control approach based on sound pressure feedback. The objective and subjective validation of this approach implemented as a prototype setup in a user-study is presented. Finally, the use of the insights from the first part for fitting a hearing aid incorporating such active occlusion control is suggested.

EPFL2014

Binaural hearing aids with wireless microphone systems including speaker localization and spatialization

Gilles André Courtois, Hervé Lissek, Patrick Marmaroli

The digital wireless microphone systems for hearing aids have been developed to provide a clean and intelligible speech signal to hearing-impaired listeners for e.g. school or teleconference applications. In this technology, the voice of the speaker is picked up by a body-worn microphone, wirelessly transmitted to the hearing aids and rendered in a diotic way (same signal at both ears), preventing any speaker localization clues from being provided. The reported algorithm performs a real-time binaural localization and tracking of the talker so that the clean speech signal can then be spatialized, according to its estimated position relative to the aided listener. This feature is supposed to increase comfort, sense of immersion and intelligibility for the users of such wireless microphone systems.

2015