The basic study on communication aids for the profoundly deaf using ultrasound hearing

探讨了骨传导超声(BCU)的感知机制。用正电子发射断层扫描(PET)和脑磁图(MEG)对BCU的中枢听觉系统进行了研究。通过对BCU1内头部声场的计算、超声波掩蔽器的研究和动态范围的研究，探讨了其外围机理。使用三维正电子发射计算机断层扫描技术，测量了5名深度失聪受试者和听力正常受试者BCU激活的皮质区域。深度失聪受试者和正常志愿者的初级听觉皮质的内侧部分被显著激活。这些结果表明，耳蜗外通路将信息传递到初级听觉皮质，因此即使在深度失聪的情况下也能产生可检测到的声音感觉。用脑磁图比较了30 kHzBCU刺激时长和1 kHz气导1 kHz短声刺激时程的影响。结果，增长的显著差异是…在饱和点以下观察较多。结果表明，BCU与可听音的中枢听觉系统可能存在一定的差异。利用时域有限差分(FDTD)技术计算了不同刺激位置的骨传导声在头部的物理现象。结果表明，BCU的头部内侧声场与骨导可听声有较大差异。在8-18 kHz的频率范围内，测量了27 khz、30 khz和33 khz骨传导超声波掩蔽器对空气传导高频声音的掩蔽量。结果表明，超声波掩蔽器对10~14 kHz的空气传导信号有较强的屏蔽作用。BCU的动态范围明显小于可听声音的动态范围。这些结果表明，BCU的感知依赖于超声波诱导的内毛细胞活动，而不依赖于外毛细胞的增强。较少

The perception mechanism of bone-conducted ultrasound (BCU) was investigated. The central auditory system of BCU was studied using PET (positron emission tomography) and magnetoencephalography (MEG). Its peripheral mechanism was investigated by means of calculation of the inner head acoustic field and the study on ultrasonic masker and dynamic range of BCU.1. Using three-dimensional PET, the cortical areas activated by BCU were measured from five profoundly deaf subjects and normal-hearing subjects. The medial portion of the primary auditory cortex of the profoundly deaf subjects as well as normal volunteers was significantly activated. These results suggest that extra-cochler routes convey information to the primary auditory cortex and can therefore produce detectable sound sensation even in the profoundly deaf.2. The effects of stimulus duration for 30 kHZ BCU were compared with those for air-conducted 1 kHz tone bursts by MEG. As a result, significant differences in the growth were … More observed below the saturation points. The results indicated a possibility that there were some differences in the central auditory system between BCU and audible sound.3. The phenomenon physically occurring within the head for bone-conducted sound of various stimulation locations has been calculated using finite-difference time-domain (FDTD) technique. The results showed that there was a large difference between the inner head acoustic field for BCU and bone-conducted audible sound.4. The mount of masking produced by 27-, 30- and 33-kHz bone-conducted ultrasonic maskers for air-conducted high-frequency sounds was measured in the frequency range of 8-18 kHz. The results showed that the air-conducted signals of 10-14 kHz were strongly masked by the ultrasonic maskers. And the dynamic range for BCU was clearly narrower than that for audible sounds. These results suggest that perception of BCU depends on inner hair cell activity induced by ultrasound, and did not depend on enhancement by the outer hair cells. Less