Evaluation of a fine structure sound-coding strategy for acoustic perception in newly cochlear implant users

Sound can be divided into 2 forms of temporal information: envelope and fine structure. While cochlear implants are effective in speech recognition in quiet, they are less effective for listening in noise and for music perception. This study aimed to compare a fine structure processing strategy (FS4) with a previous coding strategy (HDCIS) in newly implanted CI users.

This prospective, randomized, cross-over, double-blind study included 19 participants between January 2017 and July 2018. Each participant was randomized to receive a map programmed with FS4 followed by a map programmed with HDCIS or vice versa. Tonal/vocal audiometry in quiet, music perception tests (Gabrielsson scale, interval test, melodic contour identification), and quality of life (HISQUI) assessments were conducted after 1 month of adaptation to each setting.

FS4 significantly improved speech recognition in quiet (mean effect (ME) = 8.4%, 95% confidence interval (CI95%) = 3.5% to 13.2%, p = 0.004, standardized effect size (SES) = 1.06), Gabrielsson scale scores (ME = 4.8, CI95% = 0.4 to 9.1, p = 0.047, SES = 0.67), and interval perception (ME = 18 Hz, CI95% = 2.7 to 32.4 Hz, p = 0.024, SES=0.78). No significant difference was found for melodic contour identification or HISQUI. A period effect was observed for speech recognition in quiet (p = 0.002), Gabrielsson scale (p = 0.005), interval test (p = 0.032), and HISQUI (p = 0.039). Eighty percent of the participants kept the FS4 setting after the study period.

FS4 was associated with improved music perception and speech recognition in quiet compared to HDCIS in newly implanted cochlear implant users, suggesting potential advantages of fine structure processing strategies. N° West V Ethics Committee: 2016-A01952-49. December 28, 2016.