Speech Perception In Prelingual Deaf Children With A Cochlear Implant And A Hearing Aid In Opposite Ears

BackgroundHearing aid(HA) is a kind of medical equipment,which can help hearing impaired patients improve auditory communication skills.Narrowly speaking, hearing aid is an electroacoustic amplifier,which can amplify the sound and make people hear the sound or listen to the sound clearly.Hearing aids become an intervention therapy for the overwhelming majority hearing impaired patients[1].The application of bilateral hearing aid improves the quality of patients' life obviously[2-3].Due to a large number of damaged cochlear hair cells,a cochlear implant is a well-known therapeutic option for patients with profound hearing loss when the patients cannot benefit from hearing aids[4].Cochlear impant(CI) is an electronic equipment,which imitates the work of cochlear hair cells. The operational principle of CI is activating auditory nerve directly by replacing damaged or missing cochlear hair cells and turning acoustic signal into electric signal,then making people regain the auditory function. The application of CI makes more and more people get into the sound world[5].Unilateral CI provides non-symmetric hearing, which effects the late-onset auditory deprivation easily[6-7].people also have trouble in the localization of sounds, understanding speech and prosody with unilateral cochlear in daily life, especially in a noisy environment.Bimodal hearing with a CI in one ear and a hearing aid in the contralateral ear is helpful for patients to localize the sound, to enhance speech intelligibility and sound quality in their daily life. But previous research on the additional benefit provided by bimodal fittings has shown great variability among individuals, but has not confirmed the factors contributing to this variability.The possible factors are useable residual hearing with the non-implanted ear,the experience for bimodal fittings,the adjustment for bimodal fittings,and so on.Chinese is different from the western language. Pitch has a role in indistinctiing semantic,the perception of tone could affect people,s hearing largely. The research on the benefit of bimodal hearing calls for further study in china. The further analysis for the effectiveness of bimodal hearing and relationship between useable residual hearing in the non-implanted ear and bimodal advantage was made,which could provide the theoretical guidance for people with cochlear implant. ObjectiveTo evaluate the ability to perceive syllables phrases, monosyllabic words,disyllabic words for deaf children,who use a CI alone or bimodal hearing,and analysis the relationship between aided thresholds in the HA ear and bimodal effectiveness. MethodsA total of 18 children participated in our study,who wearing a CI in one ear and an HA in opposite ears. All chidren satisfied the following criterions:the time wearing hearing aid in the contralateral ear occupied more than 75% of working or studying;useable low-frequency(250Hz,500Hz) residual hearing in the opposite ears is less than 80 dB.we regulated the parameters of hearing aid and tested the aided thresholds in the HA ear.Then the recognition rate of syllables phrases, disyllabic words, monosyllabic words were tested under the aforementioned two modes. The testing ambient included both quiet and noisy background. Results1.The speech performance of chidren was expressed with Mean±standard deviation((?)±S),when wearing bimodal hearing or cochlear implant alone in quiet or noisy background.The perception of monosyllabic words were(82.67±12.23% 83.61±12.22%),disyllabic words were(76.00±16.13% 78.11±14.84%),syllables phrases were(60.11±17.18% 65.43±16.76%) with CI alone or bimodal fitting in a quiet environment.In Signal-to-noise ratio+10dB(SNR+10dB) environment, the perception of monosyllabic words were(75.50±14.12% 76.83±14.15%),disyllabic words were(68.22±17.15% 77.78±16.83%),syllables phrases were(49.39±19.26% 56.33±19.55%).The results suggested that speech performance in a quiet or a SNR+10dB environment was significantly better with bimodal hearing than with a CI alone. All were statistically significant except the recognition rate of monosyllabic words in quiet background(P<0.05).2.Pearson correlation analyses were used to examine the relationship between the bimodal advantage and aided thresholds at 250 Hz, 500 Hz, 1kHz, 2 kHz, 4kHz in the non-implanted ear for the bimodal subjects.Significant negative correlation was found between aided thresholds at 250 Hz and the bimodal advantage for the perception of monosyllabic words in quiet background(r=-0.501, P= 0.034). Significant negative correlations were also found between aided thresholds at 500 Hz and the perception of monosyllabic words in quiet background(r =-0.209,P = 0.022),disyllabic words in quiet background(r =-0.614, P = 0.077), monosyllabic words in the SNR+10dB background(r =-0.527,P = 0.025),disyllabic words in SNR+10dB background(r =-0.574, P = 0.013).In contrast, significant correlations weren't found between bimodal effectiveness and the aided thresholds at 1kHz, 2 kHz, 4kHz in the non-implanted ear in the quiet or SNR+10dB background. ConclusionBimodal hearing could provide certain advantage in speech perception for Prelingual deaf children.The low-frequency(250 Hz, 500 Hz) residual hearing in the HA ear may play a major role in bimodal advantages.Children who have some useable residual hearing in the non-implanted ear after cochlear implant could wear hearing aid.