Travel safety issues related to digital hearing aids—Assessment of the effect of compression in sound localization and distance evaluation tasks by blindfolded hearing impaired adults

Abstract

Six adults with symmetrical sensorineural hearing loss, with no visual impairment, were fitted with two digital hearing aids. The participants experimented two fitting strategies (linear vs. Wide Dynamic Range Compression (WDRC) in a double-blind design. After 1-month adaptation period, participants were blindfolded and tested. Experimental measures included a localization assessment in a sound booth and field measurements (alignment with a parallel car, detection distance of a car, distance judgment of a perpendicular car while stationary and moving). Because of varying wind conditions, group data could not be analyzed. Individual data were examined and only large fitting strategy differences were retained. For localization and alignment tasks, no difference between the two fitting strategies was noted except for one subject who showed a substantial number of front–back confusions with WDRC. In the detection distance task, one subject showed a capability of detection larger than 200 m with the linear strategy. The other subjects showed detection distance of about 60 m regardless of the fitting strategy. Even if widespread negative effect cannot be demonstrated from this study, potential risk is not eliminated.