Sakai Yuki, Karino Shotaro, Kaga Kimitaka
Department of Otolaryngology, School of Medicine, University of Tokyo, Tokyo, Japan.
Acta Otolaryngol. 2006 Sep;126(9):926-33. doi: 10.1080/00016480500536871.
A new giant magnetostrictive bone conduction transducer (GMT) measuring 8 mm (length) by 2 mm (diameter) is capable of outputting sounds over a wider range of frequencies than conventional electromagnetic transducers (EMTs). The GMT can vibrate the rat skull about 3-100 times faster than the EMT, especially above 2 kHz.
Since the GMT can generate high sound quality and output sounds above 10 kHz, we investigated the width of the frequency response of the GMT and evaluated its mechanical performance.
We chose Wistar rats to estimate the GMT performance by measuring the bone-conducted ABR and the skull vibratory velocity because their hearing frequency range extends from 0.15 kHz to 67 kHz. We also measured the bone-conducted auditory brainstem responses (ABRs) and the skull vibratory velocity of rats with the EMT. Skull vibratory velocity was measured with a laser Doppler vibrometer (LDV).
The skull vibratory velocity at the ABR threshold obtained with each transducer was within the -35 to -50 dB range (0 dB re 1 mm/s). When 1 Vpp was applied to each transducer, the GMT had a higher velocity at frequencies of 2-30 kHz, and the EMT at frequencies of 0.5-1 kHz.
一种新型的巨型磁致伸缩骨传导换能器（GMT），尺寸为8毫米（长）×2毫米（直径），与传统电磁换能器（EMT）相比，能够在更宽的频率范围内输出声音。GMT使大鼠颅骨振动的速度比EMT快约3至100倍，尤其是在2千赫以上。
由于GMT能够产生高音质并输出10千赫以上的声音，我们研究了GMT的频率响应宽度并评估了其机械性能。
我们选择Wistar大鼠，通过测量骨传导听觉脑干反应（ABR）和颅骨振动速度来评估GMT的性能，因为它们的听觉频率范围从0.15千赫延伸至67千赫。我们还测量了使用EMT的大鼠的骨传导听觉脑干反应（ABR）和颅骨振动速度。颅骨振动速度用激光多普勒测振仪（LDV）测量。
每个换能器在ABR阈值时的颅骨振动速度在-35至-50分贝范围内（0分贝相对于1毫米/秒）。当向每个换能器施加1 Vpp时，GMT在2至30千赫频率下具有更高的速度，而EMT在0.5至1千赫频率下具有更高的速度。
