Bimodal Hearing on Music and Speech with FSP and HDCIS

Abstract

Objective: 1) Evaluate the effects of bimodal listening on performance for music and speech tasks when the implanted ear uses either fine structure processing (FSP) or high-definition continuous interleaved sampling (HDCIS) strategies. 2) Understand whether the everyday listening condition of subjects affected their performance on these tasks.

Method: A double-blinded prospective study was performed on 10 adult subjects experienced with a cochlear implant (CI) and contralateral hearing aid (HA). Subjects were tested using FSP and HDCIS in bimodal and CI alone conditions. Musical instrument identification (timbre) and vowel recognition were tested. Outcomes were scored as percent correct.

Results: With a CI alone, subjects scored higher using FSP than HDCIS on timbre (51.5% to 46.5%). The effect was opposite on vowel recognition (41.2% to 46.3%). However, when bimodal, FSP had a lower performance on timbre (52.6% to 55.1%) but higher on vowel recognition (72.7% to 70.8%). The bimodal condition provided larger benefit in timbre for HDCIS than FSP (8.6% to 1.1%). Further, the improvement in the bimodal condition was significantly higher for vowel tests than for timbre regardless of strategy. Subjects with FSP as their regular strategy outperformed subjects with HDCIS in every condition for both tests.

Conclusion: The FSP processor may provide more information to users than HDCS, producing the better performance from FSP without an HA and the greater benefit for HDCIS with an HA. Using FSP regularly may improve central processing plasticity for users improving their performance with any processor.