Ogino Riki, Otsuka Sho, Nakagawa Seiji
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:2198-2201. doi: 10.1109/EMBC.2018.8512632.
Bone-conducted ultrasound (BCU) is perceived even by the profoundly sensorineural deaf and a novel hearing aid using the perception of amplitude-modulated BCU (BCU hearing aid) has been developed. In the BCU hearing aid, the vibrator is pressed onto a part of the cranial bone behind the ear (mastoid process). However, BCU can be heard on distal parts of the body; i. e., the muscle of the neck, the clavicle, and the upper limb. In this study, to assess basic properties of such distal-presented BCU hearing, hearing thresholds were measured when 30-kHz tone bursts were presented to the neck and the upper and lower arms in normal hearing participants. Further, to assess the basic capability of transferring information by the distal-presented BCU hearing, temporal modulation transfer functions (TMTFs), that reflect the temporal resolution of the hearing, were estimated for 30-kHz carrier. The results showed that BCUs presented to the distal parts, including the lower arm, can be perceived at least in the normal hearing, whereas threshold increased depending on the distance from the head. Also, the temporal resolutions of the distal-presented BCU hearing at the neck, and the upper and lower arms were comparable to that of the mastoid process of the temporal bone. These results provide useful information not only for the improvement of the existing BCU hearing aid, but also for the development of novel distal-presented BCU devices that can provide sound information selectively to the specific person who touches the device by the arms or so.
即使是极重度感音神经性聋患者也能感知骨传导超声（BCU），并且一种利用调幅BCU感知的新型助听器（BCU助听器）已被开发出来。在BCU助听器中，振动器被按压在耳后颅骨的一部分（乳突）上。然而，在身体的远端部位也能听到BCU，即颈部肌肉、锁骨和上肢。在本研究中，为了评估这种远端呈现的BCU听力的基本特性，对正常听力参与者的颈部以及上臂和下臂施加30kHz短纯音时测量了听力阈值。此外，为了评估远端呈现的BCU听力传递信息的基本能力，针对30kHz载波估计了反映听力时间分辨率的时间调制传递函数（TMTF）。结果表明，至少在正常听力情况下，施加于包括下臂在内的远端部位的BCU是可以被感知的，而阈值会随着与头部距离的增加而升高。而且，在颈部以及上臂和下臂的远端呈现的BCU听力的时间分辨率与颞骨乳突的时间分辨率相当。这些结果不仅为改进现有的BCU助听器提供了有用信息，也为开发新型远端呈现的BCU设备提供了有用信息，这种设备可以通过手臂等接触设备的特定人员选择性地提供声音信息。
