The stimulation is transmitted to the cochlear fluids by the in and out motion of the Stapedius-footplate at the oval window at the base of the Cochlea. The oval window leads into the upper chamber (Scala vestibuli) hence given inward motion will cause the fluids to be displaced downward ,Pushing downward on the Basilar membrane and a given outward motion will displaced the fluid and basilar membrane upward.
The trick is to translate this vibratory stimulation into the bending of the hair cell Stereocilia in the right direction and it will activates the sensory process .
There are some theories which explain the sensorineural mechanism of vestibular system called the Theories of hearing it is of two types
1. Traditional Theory
The Traditional theories of hearing further divided in to three types
i. Resonance place theory
ii. Temporal theory (frequency )
iii. Place -volley theory
i. RESONANCE THEORY
The Resonance theory given by (Helmholtz in 1895) The resonance theory explain the how Basilar membrane vibrations converts into the Neural signal that distinguish between different frequencies
The resonance theory proposed that Basilar membrane was constructed segment that resonated at different frequencies and these segment were arrange to location (place) along the length of the basilar membrane.
According to Resonance place theory a sound entering in the cochlea cause the vibration of this segment that are tuned to the frequency Because these resonators are laid out according to place the location of vibrating signal at which frequencies are present
ii. TEMPORAL THEORY
The temporal theory given by the (Rutherford in 1886) the temporal theory also called the telephone theory The temporal theory said that the entire cochlea responds as a whole to all frequencies instead of being activated on place-by -place basis , here all aspects of the stimulus waveform would be transmitted to the Auditory nerve ( Like a telephone receiver connected to telephone wire) and then the frequency analysis is accomplished at higher levels in the auditory system.
The resonance model of place theory and the old temporal theories that denied place coding in the cochlea were both wrong
iii. PLACE VOLLEY THEORY
The place volley principle theory was given by (Waver in 1949) This theory proposed that the several neurons operating as a group of could fire in response to each cycle of a high frequency sound. Even though none of them can do individually the place volley theory involves the combined operation of both place and temporal mechanism , The low frequencies are handled by temporal coding and high frequencies by place and interaction mechanism.
2. TRAVELING WAVE THEORY
The traveling wave theory was give by (Bekesy in 1960) This theory describe how frequency is coded by place in the cochlea. Bekesy found that the basilar membrane is not under any tension but that its elasticity is essentially uniform Because the basilar membrane get wider while moving toward the top a base and the apex is gradation of stiffness.
The sound transmitted to the cochlea develop a special kind of wave pattern on the basilar membrane that always travel from the base to apex and this is called as the traveling wave theory.
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