Binaural model-based dynamic-range compression

Abstract

Objective: Binaural cues such as interaural level differences (ILDs) are used to organise auditory perception and to segregate sound sources in complex acoustical environments. In bilaterally fitted hearing aids, dynamic-range compression operating independently at each ear potentially alters these ILDs, thus distorting binaural perception and sound source segregation. Design: A binaurally-linked model-based fast-acting dynamic compression algorithm designed to approximate the normal-hearing basilar membrane (BM) input–output function in hearing-impaired listeners is suggested. A multi-center evaluation in comparison with an alternative binaural and two bilateral fittings was performed to assess the effect of binaural synchronisation on (a) speech intelligibility and (b) perceived quality in realistic conditions. Study sample: 30 and 12 hearing impaired (HI) listeners were aided individually with the algorithms for both experimental parts, respectively. Results: A small preference towards the proposed model-based algorithm in the direct quality comparison was found. However, no benefit of binaural-synchronisation regarding speech intelligibility was found, suggesting a dominant role of the better ear in all experimental conditions. Conclusion: The suggested binaural synchronisation of compression algorithms showed a limited effect on the tested outcome measures, however, linking could be situationally beneficial to preserve a natural binaural perception of the acoustical environment.

Key Words:

• Hearing aids
• speech perception
• binaural
• dynamic compression

Acknowledgements

The authors thank Giso Grimm and Tobias Herzke for fruitful discussions and technical support. The authors thank Ray Meddis, Nick Clark, and Wendy Lecluyse for providing the BioAid algorithm, its fitting, and for helpful comments on earlier versions of this manuscript. The authors also thank Tim Jürgens for valuable input on BioAid in earlier versions of this manuscript, as well as the representative of our industry partners Rosa-Linde Fischer from Sivantos.

Declaration of interest

This work was supported by a grant of the German Ministry of Education and Research (BMBF), under project 13EZ1127D (“Model-based Hearing Aids”) and by the DFG Cluster of Excellence EXC 1077/1 “Hearing4all”.