The hearing aid is essentially an electro-acoustic amplifier. The acoustic signal is converted into an electrical signal by a microphone (microphone). After amplification by the amplifier, the electrical signal is restored by the receiver to an acoustic signal and transmitted to the human ear, as shown in Figure below. The hearing aid is mainly composed of a microphone, an amplifier, a receiver, a battery, various volume control knobs and the like.





the basic structure of digital hearing aids






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