| Objective The aim of this study is to investigate 1) whether it has significant difference between the sound field assessment of the same hearing aid by giving FM tones and filtered compound sound, and for digital hearing aid , the result of field assessment with which sound has good correlation with hearing function assessment ;2) whether it has significant difference between the result of these two sound field assessment on analogy hearing aid and digital hearing aid; and 3) whether the use of analogy hearing aids and digital hearing aids leads to different benefits in speech recognition abilities for children with hearing loss. Method Thirty 2-7 years old children with bilateral hearing aids (severe to profound) were included in the study. They take audition and speech study in Shenzhen Early Intervention Central for Children with Special Needs from April. 2002 to Jan, 2003. All children used two hearing aids behind the ear(ten used digital hearing aids, ten used analogy hearing aids, and ten used analogy hearing aids at the beginning of term but then change to digital hearing aid). On each child, we took these research as follow:1. hearing assessment: the unaided hearing was estimated by Multi-frequency Stable State Evoked Potential System, and the aided hearing was estimated in sound field by giving FM tones and then filtered compound sound ,which delivered through a loundspeaker 40-115dBHL over the range 500 to 4000Hz.2. Hearing function evaluation: The purpose of this study was to examine children' s speech recognition abilities for Shengmu and Yunmu, It was presented in background noise when the children used analogy or digital hearing aid. The speech signal was delivered through a loudspeaker located at 70?dBHL .3.Each child's voice was taken Speech spectrum analysis by Speech analysis meter and filter of Audio and Speech Rehabilitation System.1-3 were repeated in the end of the term.4. Statistical analysis was done by SPSS 10. 0. Gave the result of hearing level assessment and hearing function evaluation ANOVA among these three groups. Took Kruskal-Wallis Test to analysis the distribution of age, sex, hearing loss degree, occurring time and the time of initial worn hearing aid, and then linear regression given on the last three factors and hearing function evaluation result. Correlation analysis was given on aided hearing level and speech recognition abilities.Results Significant difference were found between the result of aided hearing level assessment by FM tones and filtered compound sound. Function evaluation shows that the speech recognition ability of children with digital hearing aids is higher than that of which worn analogy hearing aids. It has strong correlation between the result of sound field assessment with that of function evaluation for children worn digital hearing aids. Conclusions The single subject research can be used in evaluation on benefit of rehabilitation for special needs children if the marker we choose to evaluation is valid and repeatable enough. The results of this investigation suggest that filtered compound sound with special frequency is good signal to assess the children's aided hearing level especially who worndigital hearing aids. Wearing digital hearing aids can get higher speech recognition ability than wearing analogy hearing aids for children with hearing loss. To get satisfactory effect on early intervention for child with hearing loss, wearing digital hearing aids is the best choice. |
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