Evaluation of a Binaural Spatialization Method for Hearing Aids

Evaluation of a Binaural Spatialization Method for Hearing Aids, in Terms of Speech Intelligibility, Speaker Localization and Subjective Preference.

This study investigates the possible benefits of using binaural spatialization techniques in digital wireless microphone systems for hearing aids. Speech intelligibility tests, speaker localization tests and preference tests are performed. The results of a diotic (current rendering) and a binaural (suggested rendering) rendering are compared.

The signal processing laboratory (LTS2) of the Swiss Federal Institute of Technology (EPFL) has developed a new feature of sound rendering in hearing aids. This is a collaboration between EPFL and the Swiss company Phonak Communications AG. The new functionality works with the range of Roger products from Phonak, a new generation of FM systems that use a digital transmission.

FM technology refers to a type of wireless system that helps people better understand speech in noisy situations. FM systems commonly work together with a user's hearing aids, although systems are also available for those with otherwise normal hearing (such as people who suffer from APD, ADHD etc.). An FM system works like this: the person speaking wears or holds a transmitter microphone, or the transmitter is placed in the middle of the group (picking up speech from all around). Using harmless radio waves, the FM system sends speech signal(s) to the listener, who wears a tiny FM receiver behind the ear.

The new feature of such systems performs processing of the speaker's speech signal so that it renders information related to their spatial location. This so-called sound "spatialization" is a natural property of the human binaural auditory system, which allows us to localize sounds. However, this sound spatialization is not delivered by the current FM systems. Thanks to the new technology from EPFL and Phonak, it is now possible to include a binaural spatialization of the speech signal in the Roger product of Phonak hearing devices.

Inclusion Criteria

• French-native speakers and adults.
• Normal otoscopy.
• No conductive pathology.
• Normal hearing, or moderate to severe, sloping or flat, symmetrical hearing loss.
• User of bilateral Phonak hearing aids, for more than 6 months (hearing-impaired only).

Exclusion Criteria:

• History of tinnitus or hyperacusis.
• Visual impairment, after correction with glasses or not.
• History of chronic or terminal illness or psychiatric disturbance,.
• History of epilepsy or other reactions associated with the proximity to a video screen.