Researches for practical use of the ultra sound hearing system for profoundly hearing impaired patients and auditory mechanism of ultra sound

虽然我们听不到20 kHz以上的超声波，但频率上的振动可以通过骨传导(骨传导超声)诱导听觉感觉。有趣的是，骨传导超声也可以对完全听不到声音的深度听力障碍患者产生听觉感觉。利用这一现象，我们研制了骨传导超声助听器。在本研究中，我们解决了两个挑战，如(1)超声感知机制的定义和(2)骨传导超声助听器的实际实现。作为结果，阐明了外周和中枢听觉通路上的机制，例如，周围感觉器官位于耳蜗底转处，感觉器官不是对转换的可听声音而是对超声波本身做出反应，外毛细胞当时不工作。此外，对助听器的实际研究发现，语言中的调幅超声波可以表达韵律(语调)，使用助听器进行康复可以提高语言的清晰度。

Although we can not hear ultra sound above 20 kHz, the vibration in the frequency can induce auditory sensation through the bone conduction (bone-conducted ultrasound). And it is interesting that the bone-conducted ultrasound can induce auditory sensation also for profoundly hearing impaired patients who can not hear sound absolutely. Using this phenomenon, we have developed the bone-conducted ultrasound hearing aid. In this study, we addressed two challenges such as(1) definition of the mechanism of ultrasound perceptionand (2) practical realization of the bone-conducted ultrasound hearing aid.As results, the mechanisms on the peripheral and central auditory pathways were clarified; for examples, that the peripheral perceptual organs are located in the basal turn of the cochlea, the perceptual organs respond not to the transformed audible sound but to the ultrasound itself, and the outer hair cells does not work at that time. Moreover, practical researches of the hearing aid could found that the amplitude-modulated ultrasound in language can express the prosody (intonation) and the rehabilitation using the hearing aid can improve the speech intelligibility.