Development of a new electromagnetic hearing aid using lightweight coils to vibrate the ossicles via the tympanic membrane

一种新型的电磁助听器，利用附着在鼓膜上的磁铁和振子线圈之间的斥力，产生高激振力，使小听骨通过鼓膜振动。因此，为了获得高激振力，对振子线圈产生的磁场进行评估是很重要的。首先，设计了驱动线圈，向振动器线圈施加电流，使其产生最大的激振力。然后将优化设计的线圈耦合到放大器上，利用模拟人类中耳的人工中耳测量助听器产生的激振力。可以得出以下结论。当对新研制的助听器施加60 dB SPL（正常语音级）的声压时，在3 kHz以上的声压下产生100 dB SPL的激励力。这个值足以治疗高达80dB HL.2的感音神经性听力损失患者。该助听器在两个频率的激振力不足。这一结果表明放大器有进一步改进的必要。

A newly developed electromagnetic hearing aid can generate high-excitation force to vibrate ossicles via the tympanic membrane by repulsive force, which acts between the magnet and the vibrator coil attached to the tympanic membrane. Therefore, to obtain the high-excitation force, it is important to evaluate a magnetic field generated by the vibrator coil.First, a driving coil, which applies an electrical current to the vibrator coil, was designed so as to generate the greatest excitation force. Optimally designed coil was then coupled to an amplifier and the excitation force generated by the hearing aid was measured using an artificial middle ear, which simulates middle ear of the human. The following conclusions can be drawn.1. When a sound pressure of 60 dB SPL (normal speech level) was applied to the newly developed hearing aid, it generated the excitation force of 100 dB SPL in terms of sound pressure above 3 kHz. This value is sufficient to treat patients with sensorineural hearing loss up to 80dB HL.2. The excitation force of this hearing aid was not sufficient at tow frequencies. This result indicates that improvement of the amplifier is necessary further.