Development of body-conducted speech microphone using Optical Fiber Bragg Grating for supporting Magnetic Resonance Imaging operation

近年来，由于日本正在迅速老龄化，因此在医疗领域进行精确检查的必要性正在增加。因此，许多医疗诊断系统被用来进行精确的检查，以保持人们的健康。磁共振成像（Magnetic Resonance Imaging，MRI）是利用磁共振方法在医学前沿进行检查的诊断系统之一，它在成像时会产生高磁场和噪声，例如约100 dB声压级（Sound Pressure Level，SPL）以上。因此，患者和操作者之间的通信使用由非磁性材料组成的光纤布拉格光栅（OFBG）麦克风，因为房间不带由磁性材料组成的常规麦克风，但是OFBG麦克风不测量用于通信的频率特性中的信号。基于这些原因，作者提出了利用OFBG的体导语音麦克风（BCS）的发展，其中语音是对空气传导噪声的鲁棒信号，因为它很难受到噪声的影响。在研究中，信号测量的有效性与时间-频率分析相比，语音测量加速度计，如传统的BCS麦克风。实验证明，本文提出的基于差分加速度和噪声抑制的信号恢复方法能够从BCS麦克风测量的信号中提取出清晰的信号。

Recently, it is increasing the necessity of precisely inspections in the medical front because Japan is rapidly aging. Because of the reason, lots of medical diagnoses systems are employed for precisely inspections for keep the people healthy. Magnetic Resonance Imaging(MRI), one of diagnoses systems for inspection at medical front using magnetic resonance method, give out a high magnetic field and noisy sound such as about 100-dB Sound Pressure Level(SPL) above when it imagines the images. Thus, a communication between a patient and an operator is used an Optical Fiber Bragg Grating(OFBG) microphone which composed of non-magnetic materials because the room does not arrow to bring the conventional microphone composed of magnetic materials however the OFBG microphone does not measure a signal in frequency characteristics for the communication. From these reasons, the author is proposed the development of the body-conducted speech microphone(BCS) using OFBG which the speech is robust signal against air-conducted noise because it is difficult to influence by the noise. In the research, the effectiveness of signal measurement is shown with time-frequency analysis compares to the speech measured accelerometer such as a conventional BCS microphone. And it is proven the experiments that a clearly signal is estimated from the signal measured by BCS microphone for OFBG with our signal retrieval method which are used differential acceleration and noise reduction method.