The Active Model: The Effect of Stiffness on the Maximum Amplitude Displacement of the Basilar Membrane

The human cochlea is the part of the inner ear where acoustic signals are transformed into neural pulses and then signaled to the brain. The cochlear amplifier is essentially a positive feedback loop within the cochlea that amplifies the traveling wave, this mechanism based on the cochlea's microanatomy, as well as, outer hair cell force, to account for the cochlea's characteristic behavior. A proposed theory of the active cochlea that the feed-forward/feed-backward are two mechanisms for the outer hair cell force amplification where an expanding hair cell gives a forward push through the Deiters Cells and a backward pull on the Basilar membrane through the Phalangeal process.Many important questions of cochlea mechanics are mathematically complicated, however, they can be studied using numerical simulations. Genetic mutations of type IV collagen lead to a malfunction of Basilar Membrane, resulting in the hearing loss associated with Alport Syndrome, which is a disease that affects the cochlea due to the abnormal structure of the Basilar Membrane (it becomes stiffer). Therefore, a mathematical model of the BM was developed to investigate and show numerically the effect of the stiffness on its structure with the objective to study the ear dysfunction in the active cochlea.