Localization and Amplification
Kuk and Korhoen define localization as “the ability to tell the direction of a sound source” in three dimensional space. They report that the ability to localize sounds presents a more comfortable and natural listening experience, enhances safety, and allows the person listening to face the sound source, thus enhancing visual cues, too. Of note, sensorineural hearing loss (SNHL) reduces localization ability, and hearing aids may not restore normal localization ability. Of note, when aided, left/right localization is most often not significantly affected by SNHL, however front/back discriminations are more often problematic and may be worse aided than unaided, particularly at comfortable listening levels. The authors note that hearing aids cannot overcome the distortions within the auditory system, and hearing aid wearers often develop compensatory strategies. Kuk and Korhoen report that wide dynamic range compression (WDRC) hearing aids provide the most gain to the quietest sounds and less gain to loud sounds, which reduces the natural interaural loudness differences (ILDs). ILDs offer significant information with regard to knowing where sounds originate.
With regard to how to improve localization via hearing aids, the authors recommend the following: (1) bilateral fittings, (2) wireless hearing aids with connectivity (allowing nearly real-time communication between the two hearing aids) to maximally preserve ILDs, (3) restoring pinna cues in BTE and RIC products (to improve front/back identification), (4) use of slow acting compression, (5) use of broad bandwidth (extended bandwidth) and open fits, and (6) aural rehabilitation programs to train (or re-train) the brain to use the acoustic cues provided.
For More Information, References, and Recommendations
Beck DL, Sockalingham R. (2010) Facilitating Spatial Hearing Through Advanced Hearing Aid Technology. Hearing Review.
Beck DL, Olsen J. Extended bandwidths in hearing aids. Hearing Review 15(11):22-26.
Kuk F, Korhonen P. (2014) Localization 101–Hearing Aid Factors in Localization. Hearing Review. August 21.
Neher T, Behrens T, Beck DL. (2008) Spatial hearing and understanding speech in complex environments. Hearing Review. 15(12):22-25.