Study for practical use of a digital hearing aid device having functions of speech rate convertion and intonation emphasis

本研究的目的是研制一种具有语速转换和语调加重功能的老年人数字助听器。研究结果如下：1.设计了一种具有语速转换功能的数字助听器，并对老年听力障碍者进行了助听效果评价。从实验结果来看，当转换率为普通语音速率的1.5倍时，日语单词的识别率提高了3倍。我们与日立公司合作开发了一款具有语速转换功能的便携式助听器.以老年听力障碍者为被试，测试其语调变化的辨别能力。从结果来看，这种能力比正常人差得多。此外，当字词的语调被强调时，老年听障者的语调辨别能力也会增加。这意味着语调强调对听力受损者是有效的。特别是对于有前调的汉语口语，这种强调方式更有借鉴意义.我们发现，音高波动，这是一个小的语调变化，具有1/f波动的特点。预期将波动添加到助听器功能将有助于改善语音质量。此外，小波变换的方法被证明是有效的控制音调波动和转换算法被成功地存储到数字信号处理器的助听器。通过研究，阐明了1/f波动和小波变换算法对改善老年听力障碍者数字助听器是非常有用的。

The purpose of this study is to develop a digital hearing aid, which has functions of speech rate conversion and intonation emphasis, for the elderly impaired. Research results are as follows.1. The digital hearing aid having a function of the speech rate conversion was designed and this hearing aid was evaluated by the elderly hearing impaired. From the experimental results, the recognition rate of the Japanese words increased 3 times when the conversion rate was 1.5 times of the ordinary speech rate. We have developed a portable hearing aid having the speech rate conversion function in cooperation with Hitachi company.2. Discrimination ability of the intonation change was tested by the elderly hearing impaired. From the results, the ability was found to be much worse than the normal subjects. Furthermore, the intonation discrimination ability of the elderly hearing impaired was found to increase when the intonation of the words was emphasized. This means that the intonation emphasis was effective for the hearing impaired. Especially, the emphasis would be useful for Chinese spoken language which has fore tones.3. We have found that pitch fluctuation, which is small intonation change, has characteristics of 1/f fluctuation. It was anticipated that the addition of the fluctuation to the hearing aid function would be useful to improve the quality of speech. Furthermore, a wavelet conversion method was proved to be effective to control the pitch fluctuation and the conversion algorithm was successfully stored into a digital signal processor of the hearing aid. Through the study, it was clarified that the 1/f fluctuation and the wavelet conversion algorithm are very useful to improve the digital hearing aid for the elderly hearing impaired.