Focus on bimodal cochlear implant users: The advantages of a dedicated fitting formula

Abstract Aim: The aim is to evaluate the advantages of the dedicated Adaptive Phonak Digital Bimodal (APDB) fitting formula compared to the traditional National Acoustic Laboratories Non-Linear 2 (NAL-NL2) for contralateral hearing aid (HA) in bimodal cochlear implant (CI) users. Settings and Design: Cross-over bicentric study involving 10 adult bimodal Advanced Bionics CI users with usable contralateral hearing. Subjects and Methods: Participants were provided with a dedicated Naída Link Q90 HA. Speech recognition in noise was assessed with the Italian Matrix Sentence Test. The competing noise was presented at a fixed level of 55 dB HL. The speech level was changed adaptively to calculate the signal-to-noise ratio (SNR) targeting at a score of 50% correct words. Outcomes were compared in three configurations, with CI only, with APDB and with NAL-NL2. Subjective hearing benefit was assessed using the Speech, Spatial and Qualities of Hearing Scale (SSQ) questionnaire in both bimodal configurations. Results: Speech intelligibility in noise showed significantly better results for both bimodal configurations ( P < 0.001) compared to CI only (mean 9.1 dB SNR ± 5.7) and for the APDB formula (mean 2.25 dB SNR ± 2.4) compared to NAL-NL2 (mean 3.3 dB SNR ± 2.7; P < 0.05). Responses to the SSQ demonstrated a trend for improvement with APDB compared to NAL2/NAL in the “space” subgroup and a statistically significant difference in favor of APDB for “other sound qualities” ( P < 0.05). Conclusions: The APDB fitting formula has been shown to be beneficial for binaural bimodal CI users, both in speech intelligibility test results and subjective perception of hearing comfort.