Application of Signals with Rippled Spectra as a Training Approach for Speech Intelligibility Improvements in Cochlear Implant Users.

In cochlear implant (CI) users, the discrimination of sound signals with rippled spectra correlates with speech discrimination. We suggest that rippled-spectrum signals could be a basis for training CI users to improve speech intelligibility. Fifteen CI users participated in the study. Ten of them used the software for training (the experimental group), and five did not (the control group). Software based on the phase reversal discrimination of rippled spectra was used. The experimental group was also tested for speech discrimination using phonetic material based on polysyllabic balanced speech material. An improvement in the discrimination of the rippled spectrum was observed in all CI users from the experimental group. There was no significant improvement in the control group. The result of the speech discrimination test showed that the percentage of recognized words increased after training in nine out of ten CI users. For five CI users who participated in the training program, the data on word recognition were also obtained earlier (at least eight months before training). The increase in the percentage of recognized words was greater after training compared to the period before training. The results allow the suggestion that sound signals with rippled spectra could be used not only for testing rehabilitation results after CI but also for training CI users to discriminate sounds with complex spectra.

Clinical validation of the Russian Matrix test - effect of hearing loss, age, and noise level.

OBJECTIVE: To validate the Russian matrix sentence test (RUMatrix) for the assessment of speech recognition in quiet and in noise in clinical praxis. The effect of hearing impairment, age, and masking-noise level on speech recognition was examined. DESIGN: All participants underwent pure tone audiometry, a monosyllabic speech test in quiet, and speech recognition measurements with RUMatrix in quiet (SRTQ) and in noise (SRTN). STUDY SAMPLE: One hundred and forty-two listeners divided into four groups: 1. Young normal-hearing listeners, 2. Older normal-hearing listeners, 3. Young hearing-impaired listeners, and 4. Older hearing-impaired listeners. RESULTS: Significant differences between groups of listeners were found in the SRTQ and SRTN. A strong correlation between hearing threshold and SRTQ (R2=0.88, p < 0.001) indicates a strong link between speech recognition in quiet and audibility. The pure-tone average explained less variance in SRTN (R2=0.67, p < 0.001), pointing out an additional influence of suprathreshold distortion. A high test sensitivity of 0.99 was found for SRTN and SRTQ. The monosyllabic test had a low sensitivity (0.21), indicating that the test is not suitable for separating normal-hearing and hearing-impaired listeners. CONCLUSIONS: RuMatrix is a reliable speech recognition assessment tool with a high sensitivity and validity for the main aspects of hearing impairment.