Plinkert P K, Baumann J W, Lenarz T, Keiner S, Leysieffer H, Zenner H P
Department of Otorhinolaryngology, University of Tübingen, Germany.
Eur Arch Otorhinolaryngol. 2000;257(6):304-13. doi: 10.1007/s004059900209.
We have recently developed an implantable piezoelectric hearing aid transducer that is suitable for implantation in patients with sensorineural hearing loss. The transducer does not transmit sound but conducts micromechanical vibrations to the cochlea. In ten cat ears we investigated the efficiency of the implantable transducer with respect to the direct transfer of vibrations within the audible frequency range via the ossicles to the cochlea or directly into the vestibule. The acoustically evoked brainstem potential (ABR) threshold was determined prior to implantation, and the middle ear was then opened and the piezoelectric transducer coupled to the ossicles or to the perilymph. Acoustically evoked brainstem potentials were recorded following stimulation at the umbo, long process of the incus, stapes head, stapes foot plate, and in the vestibulum. Comparisons of the acoustically and mechanically evoked thresholds revealed a good correlation of the two stimulation levels. An electrical transducer voltage of 1 V(RMS) produced equivalent sound pressure levels (SPL) of 100-128 dB at the tympanic membrane. To assess the hearing we compared stimulus-dependent latencies of the early potentials (peaks P1-P5) and thresholds. This evaluation was based on four ears with normal hearing in which the piezoelectric transducer was coupled to the long process of the incus. The mean values of the latencies and their scattering range correlated extremely well in the two stimulation modes. They were nearly identical when the equivalent SPL of 100 dB was assigned to the maximally applied electrical level of 0 dB. These in vitro and in vivo findings demonstrate that the characteristics of the transducer warrant its development further from the prototype stage to become a component of an implantable hearing device for patients with sensorineural hearing loss.
我们最近研发出一种可植入式压电助听器换能器，适用于植入感音神经性听力损失患者体内。该换能器不传播声音，而是将微机械振动传导至耳蜗。在十只猫耳中，我们研究了可植入式换能器在可听频率范围内通过听小骨将振动直接传递至耳蜗或直接传入前庭的效率。在植入前测定听觉诱发脑干电位（ABR）阈值，然后打开中耳，将压电换能器与听小骨或外淋巴相连。在鼓膜脐、砧骨长突、镫骨头、镫骨底板以及前庭进行刺激后记录听觉诱发脑干电位。对听觉和机械诱发阈值的比较显示两种刺激水平具有良好的相关性。1 V（RMS）的电换能器电压在鼓膜处产生100 - 128 dB的等效声压级（SPL）。为评估听力，我们比较了早期电位（P1 - P5峰）的刺激依赖性潜伏期和阈值。该评估基于四只听力正常的耳朵，其中压电换能器与砧骨长突相连。在两种刺激模式下，潜伏期的平均值及其离散范围相关性极佳。当将100 dB的等效SPL指定为最大施加电平0 dB时，它们几乎相同。这些体外和体内研究结果表明，该换能器的特性使其有必要从原型阶段进一步发展，成为感音神经性听力损失患者可植入式听力装置的一个组件。
