Loudness Balancing Optimization for Better Speech Intelligibility, Music Perception, and Spectral Temporal Resolution in Cochlear Implant Users

Abstract

Hypothesis The behaviorally based programming with loudness balancing (LB) would result in better speech understanding, spectral–temporal resolution, and music perception scores, and there would be a relationship between these scores. Background Loudness imbalances at upper stimulation levels may cause sounds to be perceived as irregular, gravelly, or overly echoed and may negatively affect the listening performance of the cochlear implant (CI) user. LB should be performed after fitting to overcome these problems. Methods The study included 26 unilateral Med-EL CI users. Two different CI programs based on the objective electrically evoked stapedial reflex threshold (P1) and the behaviorally program with LB (P2) were recorded for each participant. The Turkish Matrix Sentence Test (TMS) was applied to evaluate speech perception; the Random Gap Detection Test (RGDT) and Spectral-Temporally Modulated Ripple Test (SMRT) were applied to evaluate spectral temporal resolution skills; the Mini Profile of Music Perception Skills (mini-PROMS) and Melodic Contour Identification (MCI) tests were applied to evaluate music perception, and the results were compared. Results Significantly better scores were obtained with P2 in TMS tests performed in noise and quiet. SMRT scores were significantly correlated with TMS in quiet and noise, and mini-PROMS sound perception results. Although better scores were obtained with P2 in the mini-PROMS total score and MCI, a significant difference was found only for MCI. Conclusion The data from the current study showed that equalization of loudness across CI electrodes leads to better perceptual acuity. It also revealed the relationship between speech perception, spectral–temporal resolution, and music perception.