Scientific Article

Modeling of speech-dependent own voice transfer characteristics for hearables with an in-ear microphone

¹ Fraunhofer Institute for Digital Media Technology IDMT, Oldenburg Branch for Hearing, Speech and Audio Technology HSA, Marie-Curie-Straße 2, 26129 Oldenburg, Germany
² Carl von Ossietzky University of Oldenburg, Department of Medical Physics and Acoustics and Cluster of Excellence Hearing4all, Carl-von-Ossietzky-Straße 11, 26129 Oldenburg, Germany

^* Corresponding author: mattes.ohlenbusch@idmt.fraunhofer.de

Received: 22 March 2024
Accepted: 27 June 2024

Abstract

Many hearables contain an in-ear microphone, which may be used to capture the own voice of its user. However, due to the hearable occluding the ear canal, the in-ear microphone mostly records body-conducted speech, typically suffering from band-limitation effects and amplification at low frequencies. Since the occlusion effect is determined by the ratio between the air-conducted and body-conducted components of own voice, the own voice transfer characteristics between the outer face of the hearable and the in-ear microphone depend on the speech content and the individual talker. In this paper, we propose a speech-dependent model of the own voice transfer characteristics based on phoneme recognition, assuming a linear time-invariant relative transfer function for each phoneme. We consider both individual models and models averaged over several talkers. Experimental results based on recordings with a prototype hearable show that the proposed speech-dependent model enables to simulate in-ear signals more accurately than a speech-independent model in terms of technical measures, especially under utterance mismatch and talker mismatch. Additionally, simulation results show that talker-averaged models generalize better to different talkers than individual models.