Advantages And Disadvantages Of Artificial Cochlea

1. Introduction

Sensorineural hearing loss (SNHL) is a type of deafness which is often caused by the damage on hair cells of cochlea in inner ears. Hair cells convert acoustic sounds to electrical signals and stimulate auditory nerves. The clinical treatment for the hearing loss in both children and adults is by using the artificial cochlea. This device bypasses the damaged hair cells by generating the electric current in response to acoustic sound. Current artificial cochlea consist of an implantable electrode array for the stimulation and an extracorporeal device including a microphone [1], a sound processor and a battery. Acoustic sound is detected and analyzed with respect to frequency of extracorporeal device. Signals are processed and transferred through a transcutaneous system. Auditory nerves are simulated through electrodes inserted in the cochlea. Disadvantages include the indispensability of extracorporeal devices, the small number of electrodes which closely connects to the limitation of tones, and the relatively large power consumption [1].

2. Functions and anatomy of the cochlea

The functions of the cochlea include the conversion of acoustic wave signals to electrical signals and the frequency selectivity. The basilar membrane (BM) is a biological diaphragm in the cochlea has an important role in frequency selectivity. The mammalian ear is composed of three parts: the outer, the middle, and inner ears (Fig

The location of the largest vibration in the basilar membrane depends on the frequency of the travelling wave (Fig 1E). Width, thickness, and stiffness of the basilar membrane vary along the length of the cochlear spiral [2]. Due to this variation in impedance (mechanical), high frequency sounds amplify the motion of the basilar membrane near the base of the cochlea, whereas low frequency sounds amplify its motion near the apex (Fig 1E)