Evaluation of the cochlear implantation users rehabilitation results using psychoacoustic methods

Abstract

To investigate the correlation of the speech intelligibility in quiet with frequency resolving power (FRP) of hearing using a ripple-spectrum phase reversion test (RSPRT) in CI users. The study includes 30 CI users, three of them after bilateral CI, aged from 13 to 63 years with CI usage experience from 1 year to 16 years. 19 patients used CI systems manufactured by Cochlear Ltd. (Australia), 11 patients used CI systems manufactured by Advanced Bionics (Switzerland). All subjects underwent a number of studies including pure tone audiometry (TPA), speech audiometry in quiet using a multi-syllable speech material on a two-channel clinical audiometer AC-40 (Interacoustics A/S, Denmark); PC with recorded phonetic material from which the signal was reproduced, acoustic speaker SP90 (Interacoustics A/S, Denmark), for FRP estimation - RSPRT test in a free sound field, which was installed on the PC and also reproduced through SP 90 speakers (Interacoustics A/S, Denmark) were used. According to TPA results in a free sound field, the sound perception thresholds in all subjects corresponded to the mild degree sensorineural hearing loss. The sound perception threshold in the free sound field in the range from 500 Hz to 4 kHz was within the range of 25-30 dB nHL. The percentage of speech intelligibility in quiet in the free sound field ranged from 5 to 100%. During the FRP study of patients using RSPRT test, the following results were obtained: the average value of RSPRT test results at the frequency of 1 kHz was 1.94 RPO; for 2 kHz - 2.3 RPO; for 4 kHz - 2.2. The significant correlation between the speech intelligibility in quiet and frequency resolution of hearing was obtained at 1 and 4 kHz. The highest correlation coefficient was detected at 1 kHz - r=0.57 (p=0.0005), while at 4 kHz it was lower - r=0.46 (p=0.009), and at 2 kHz - at the boundary of the significance: r=0.34 (p=0.051). As a result of the study, it was found that there is a correlation between speech intelligibility in quiet and FRP of hearing, which makes it possible to recommend the use of RSPRT in assessing the auditory rehabilitation of patients after CI.