Shimokura Ryota, Nishimura Tadashi, Hosoi Hiroshi
Department of Systems Science, Graduate School of Engineering Science, Osaka University, D436, 1-3 Machikaneyama, Toyonaka 560-8531, Osaka, Japan.
Otolaryngology-Head & Neck Surgery, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Nara, Japan.
Audiol Res. 2023 Nov 9;13(6):898-909. doi: 10.3390/audiolres13060078.
Cartilage conduction is known widely as a third hearing transmission mechanism after the air and bone conduction methods, and transducers dedicated to the production of cartilage conduction sounds have been developed by several Japanese companies. To estimate the acoustic performance of the five cartilage conduction transducers selected for this study, both airborne sounds and cartilage conduction sounds were measured. Airborne sounds can be measured using a commercial condenser microphone; however, cartilage conduction sounds are impossible to measure using a conventional head and torso simulator (HATS), because the standard-issue ear pinna simulator cannot reproduce cartilage conduction sounds with the same spectral characteristics as the corresponding sounds measured in humans. Therefore, this study replaced the standard-issue simulator with a developed pinna simulator that can produce similar spectral characteristics to those of humans. The HATS manipulated in this manner realized results demonstrating that transducers that fitted the entrance to the external auditory canal more densely could produce greater cartilage conduction sounds. Among the five transducers under test, the ring-shaped device, which was not much larger than the entrance to the canal, satisfied the spectral requirements.
软骨传导作为继空气传导和骨传导方法之后的第三种听力传输机制已广为人知，几家日本公司已开发出专门用于产生软骨传导声音的换能器。为了评估本研究中所选的五个软骨传导换能器的声学性能，对空气传播声音和软骨传导声音都进行了测量。空气传播声音可以使用商用电容式麦克风进行测量；然而，使用传统的头部和躯干模拟器（HATS）无法测量软骨传导声音，因为标准配备的耳廓模拟器无法再现与在人类中测量的相应声音具有相同频谱特性的软骨传导声音。因此，本研究用一种开发的耳廓模拟器取代了标准配备的模拟器，该模拟器可以产生与人类相似的频谱特性。以这种方式操作的HATS实现的结果表明，更紧密地贴合外耳道入口的换能器可以产生更大的软骨传导声音。在所测试的五个换能器中，尺寸不比耳道入口大多少的环形装置满足频谱要求。
