Purpose: One of the major reasons that totally implantable cochlear microphones are not readily available is the lack of good implantable microphones. An implantable microphone has the potential to provide a range of benefits over external microphones for cochlear implant users including the filtering ability of the outer ear, cosmetics, and usability in all situations. This paper presents results from experiments in human cadaveric ears of a piezofilm microphone concept under development as a possible component of a future implantable microphone system for use with cochlear implants. This microphone is referred to here as a drum microphone (DrumMic) that senses the robust and predictable motion of the umbo, the tip of the malleus. Methods: The performance was measured of five DrumMics inserted in four different human cadaveric temporal bones. Sensitivity, linearity, bandwidth, and equivalent input noise were measured during these experiments using a sound stimulus and measurement setup. Results: The sensitivity of the DrumMics was found to be tightly clustered across different microphones and ears despite differences in umbo and middle ear anatomy. The DrumMics were shown to behave linearly across a large dynamic range (46 dB SPL to 100 dB SPL) across a wide bandwidth (100 Hz to 8 kHz). The equivalent input noise (0.1-10 kHz) of the DrumMic and amplifier referenced to the ear canal was measured to be 54 dB SPL and estimated to be 46 dB SPL after accounting for the pressure gain of the outer ear. Conclusion: The results demonstrate that the DrumMic behaves robustly across ears and fabrication. The equivalent input noise performance was shown to approach that of commercial hearing aid microphones. To advance this demonstration of the DrumMic concept to a future prototype implantable in humans, work on encapsulation, biocompatibility, connectorization will be required.

翻译：目的：完全植入式人工耳蜗麦克风尚未广泛应用的主要原因之一是缺乏性能优良的可植入麦克风。相较于体外麦克风，可植入麦克风为人工耳蜗使用者提供了包括外耳滤波功能、美观性及全场景适用性等多重优势。本文展示了一种正在研发中的压电薄膜麦克风概念在人类颞骨尸体标本中的实验结果，该技术有望成为未来人工耳蜗植入式麦克风系统的组成部分。该麦克风被命名为鼓膜麦克风（DrumMic），通过感知锤骨末端（锤骨尖）稳固且可预测的运动实现工作。方法：在四具不同人类颞骨尸体标本中植入五个鼓膜麦克风并进行性能测量。实验采用声音刺激与测量装置，评估灵敏度、线性度、带宽及等效输入噪声等指标。结果：尽管不同标本的锤骨尖及中耳解剖结构存在差异，鼓膜麦克风在跨麦克风与跨耳测试中展现出高度聚集的灵敏度分布。该麦克风在宽动态范围（46 dB SPL至100 dB SPL）及宽频带（100 Hz至8 kHz）内保持线性响应。经外耳道参考校准，鼓膜麦克风与放大器的等效输入噪声（0.1-10 kHz）实测值为54 dB SPL，计入外耳压力增益后估算值为46 dB SPL。结论：实验证明鼓膜麦克风在不同耳部结构及制造工艺下均具有稳健性能。其等效输入噪声表现已接近商用助听器麦克风水平。为将当前概念验证推进至未来可植入人体的原型阶段，还需在封装技术、生物相容性及连接器开发等方面开展进一步研究。