Speech Understanding in Quiet and Noise in Bilateral Users of the MED-EL COMBI 40/40+ Cochlear Implant System

TLDR

The study aimed to evaluate speech comprehension in quiet and noisy environments among adults bilaterally implanted with MED‑EL cochlear implants. Nine bilaterally implanted adults were tested in three configurations—both implants, right only, left only—using monosyllable and sentence tests in quiet and 10‑dB‑SNR noise presented from front, with noise from 90° or 270° azimuth. Bilateral stimulation significantly improved speech scores, with sentence comprehension 31.1 pp higher than the implant ipsilateral to noise and 10.7 pp higher than the contralateral implant, monosyllable recognition 18.7 pp higher, and all differences statistically significant (p < 0.05).

Abstract

The purpose of the study was to investigate speech understanding in quiet and noise in subjects bilaterally implanted with multi-channel cochlear implants.Nine adults bilaterally implanted with MED-EL implants were included in the study. The subjects were tested in three conditions: with both implants, with the right implant only, and with the left implant only. Speech tests included monosyllables in quiet and sentences in noise (10 dB signal to noise ratio). Speech was presented from the front, and noise was presented from either 90 degrees or 270 degrees azimuth.All subjects reported benefit from bilateral stimulation. Speech scores for all subjects were higher with bilateral than with unilateral stimulation. The average score across subjects for sentence understanding was 31.1 percentage points higher with both cochlear implants compared with the cochlear implant ipsilateral to the noise, and 10.7 percentage points higher with both cochlear implants compared with the cochlear implant contralateral to the noise. The average score for recognition of monosyllabic words was 18.7 percentage points higher with both cochlear implants than with one cochlear implant. All of these differences in average scores were significant at the 5% level.Bilateral cochlear implantation provides a significant benefit in speech understanding in both quiet and noise.