Related Experiment Video
Updated: Sep 9, 2026
Systematic Hearing Performance Evaluation Process for Adolescents with Cochlear Implantation at Early Ages
Published on: March 24, 2023
Evaluation of Fine Structure Coding in New Cochlear Implant Users with Tonotopic Fitting: a Prospective, Randomized,
Creff Gwenaelle1,2, Bernard-LE Liboux Nicolas3, Bourdon Hermine3,4
1Department of Otolaryngology-Head and Neck Surgery, University Hospital, Rennes, France. gwenaelle.Creff@chu-rennes.fr.
Objectives.:
Several studies have demonstrated the benefits of tonotopic fitting on speech-in-noise perception in new cochlear implant (CI) users. However, these studies used different coding strategies (CIS, HDCIS, FSP, FS4, or mixed) with different frequency spectra. The aim of this study was to assess the impact of fine structure (FS) cues on speech perception in noise and in quiet and music perception, in new CI users with a tonotopic fitting map.
Methods.:
A prospective, randomized, double-blind, 2-period crossover study was performed from April 2023 to June 2024. All participants had tonotopic fitting determined by using flat-panel computed tomography (CT) and reconstruction software based on the Greenwood function. 24 new CI users aged 18 years or older with either bilateral severe-to-profound sensorineural hearing loss or complete hearing loss for less than 5 years were recruited at a single tertiary referral center. Participants were randomized to FS followed by conventional coding, or the reverse sequence, for 6-week periods with speech and music assessments after each period.
Results.:
FS cues significantly improved speech recognition in noise for high signal-to-noise ratio (SNR = +9 dB, Mean Effect (ME) = 6.0%, Standardized effect size (SES) = 0.62, p = 0.010). A period effect was observed beyond + 6 dB of SNR (SNR = +9 dB, p = 0.010; SNR = +6 dB, p = 0.018) without a statistically significant group effect. Speech recognition and tonal audiometry in quiet were not affected by FS coding. Melodic contour identification was enhanced by FS cues (ME = 7.2%, SES = 0.51, p = 0.030), and, in an exploratory subset analysis, low-frequency pitch discrimination was also improved (ME = 8.5 Hz, SES = 0.72, p = 0.04). Over 75% of the participants retained the tonotopic map with FS coding after study completion.
Conclusion.:
FS coding strategies on tonotopic maps may improve speech recognition in noise at favorable SNRs, without compromising speech understanding in quiet. It may also enhance selected complex sound perception aspects, particularly pitch- and contour-related processing, while benefits for subjective music perception appear less consistent.
