An evaluation of the performance of two binaural beamformers in complex and dynamic multitalker environments

Abstract

Objective: Binaural beamformers are super-directional hearing aids created by combining microphone outputs from each side of the head. While they offer substantial improvements in SNR over conventional directional hearing aids, the benefits (and possible limitations) of these devices in realistic, complex listening situations have not yet been fully explored. In this study we evaluated the performance of two experimental binaural beamformers. Design: Testing was carried out using a horizontal loudspeaker array. Background noise was created using recorded conversations. Performance measures included speech intelligibility, localization in noise, acceptable noise level, subjective ratings, and a novel dynamic speech intelligibility measure. Study sample: Participants were 27 listeners with bilateral hearing loss, fitted with BTE prototypes that could be switched between conventional directional or binaural beamformer microphone modes. Results: Relative to the conventional directional microphones, both binaural beamformer modes were generally superior for tasks involving fixed frontal targets, but not always for situations involving dynamic target locations. Conclusions: Binaural beamformers show promise for enhancing listening in complex situations when the location of the source of interest is predictable.

Key Words::

• Binaural beamformers
• directional hearing aids
• dynamic environments

Acknowledgements

The authors would like to thank Markus Hofbauer and Gabriel Koenig for their critical input, and Cong Van Nguyen for technical assistance.

Declaration of interest: This work was supported by Phonak AG and the Australian Government Department of Health. Virginia Best was also partially supported NIH/NIDCD grants DC04545 and DC013286. Portions of the work were presented at the World Congress of Audiology, Brisbane, Australia, May 2014.

Appendix

Appendix A. Response sheet for subjective ratings.

Note that the first three questions were answered twice, once for program A and once for program B.

While listening to the conversation in noise, the background noise is

5 Not noticeable

4 Somewhat noticeable

3 Noticeable but not intrusive or distracting

2 Fairly conspicuous, somewhat intrusive or distracting

1 Very conspicuous, very intrusive or distracting

While listening to the conversation in noise, the target talker is

5 Very clear

4 Rather clear

3 Somewhat clear

2 Rather unclear

1 Very unclear

While listening to the conversation in noise, the general quality feels

5 Very natural

4 Fairly natural

3 Somewhat natural

2 Fairly unnatural

1 Very unnatural

My overall rating of device A compared to device B is

3 A is much better

2 A is better

1 A is slightly better

0 They are about the same

− 1 B is slightly better

− 2 B is better

− 3 B is much better