Functional Status of Hearing Aids in Bilateral-Bimodal Users

Abstract

To assess the functional status of the hearing aid (HA) in bilateral-bimodal users, in whom HA monitoring is often neglected because fitting efforts are focused on the cochlear implant (CI). Also, to define an audiometric pattern of residual hearing that might explain why, despite nonoptimal bimodal fitting, certain cochlear implantees still opt to use a HA. Retrospective case review. Ambulatory care clinic. Experienced bimodal (CI/HA) adult users (N = 31) who use their HA during most of their waking hours. HA settings were required to meet a selected prescriptive (NAL-NL1) electro-acoustical Verifit Speechmap target at low frequencies using the simulated real-ear mode. After initial evaluation, HAs that did not meet the Speechmap target underwent appropriate fitting and reevaluation. Number of patients whose HAs met the defined Speechmap criteria after refitting; residual hearing levels in patients who achieved optimal bimodal fitting and in those who did not. At initial evaluation, the HA in 25 (81%) of the 31 participants was malfunctioning or poorly tuned. After HA replacement or retuning, 19 participants (61%) met the Speechmap targets, and 12 (39%) did not. However, the 2 groups had similar mean levels of unaided and aided residual hearing thresholds at 250 or 500 Hz. To maximize the benefit for bilateral-bimodal users, specific guidelines must be established also for fitting of their HAs. The focus should be on achieving the maximum amplification possible at low frequencies.