The sound energy transmitted to the kohlea after the base of the stapes and the scale vestibule first activates the perilenfi. After this phase, two important tasks of the kohlea begin. The first is transmission. In other words, it is the transport of acoustic energy to the hair cells in the corti organ.
The second is transformation. In other words, it is the event that the mechanical conduction wave coming to the feather cells in the corti organ is converted into chemical or electrical voltages and given to the hearing nerve. This transformation takes place in such a way that the physical features of the sound such as pitch, timbre, phase separation, and intensity will not be lost, and these features in the sound energy are encoded by the electrical voltages that will occur and sent to the central nervous system.
According to Bekesy, auditory vibrations applied to any of the scales lead to displacements in the basilar membrane, which is called progressive wave theory. This wave starts from the basal end of the basilar membrane and moves towards the apex. The spread is in both longitudinal and transverse directions. Again, the most important feature of this transmission wave is that its amplitude increases gradually and reaches its maximum, and the vibrations later fade and change phase.
Vortex movements begin in liquids after the largest vibration zone. Another important feature is that where these waves make the greatest vibration on the basilar membrane, certain regions are formed for each frequency. This is transmitted to the hearing center with nerve impulses. High tones end deep in the hearing center, and low tones end on their surface.