Hearing is one of the five main human senses, along with sight, smell, taste and touch. Hearing is a sense in charge of picking up the sounds (longitudinal waves), coming from outside of the human body and to transmit them, through a complex mechanism, that originates in the ear, the temporal cortex, and then to the area of the brain that can receive and decode them. The sound waves are converted from longitudinal waves into nerve impulses that are later interpreted by the brain. The normal human ear can detect sounds with frequencies that range from 20 Hz to about 20,000 Hz but is most sensitive to sounds around the 1500 to 3000 Hz frequency range. This is the most used frequency in speech. Hearing deficits can appear when sounds waves are not properly conducted to the cochlea, when lesions interrupt the workings of the cochlear nerve or when the central nervous system pathways are involved in the processing of injured auditory stimuli. The loss of hearing is classified by conductive, sensorineural or mixed, which depend of what part of the pathway is affected.
What is hearing?
A peripheral section and a central section form the auditory apparatus in the human body. The peripheral auditory system, in turn, is formed by the outer ear and inner ear, each with its own unique role. Connecting the middle ear with the nasopharynx is the Eustachian tube, in which air enters to equalize the pressure, on both sides of the tympanic membrane, which is the eardrum. Also called audition.
The outer ear consists of the pavilion and the external ear canal that are responsible for picking up sound waves, and directing them towards the eardrum.
The middle ear has the task of picking up vibrations from the eardrum and then transmitting them to the inner ear, through the process of three tiny bones, which are the hammer, anvil and stirrup.
The inner ear, also known as the labyrinth has a complex shape that characterizes it and has the task of amplifying auditory information received and translating it into a neuron message: it is formed before the screw (or nut) and behind the vestibule and the semicircular ducts (the screw contributes to the sense of hearing, while the vestibule and products are involved in the sense of balance).
The central auditory system consists of the auditory nerve (or cochlear vestibule or the eighth cranial nerve) and the temporal cortex, which is the part of the brain that is deputed to sound perception. The task of the auditory nerve is to transmit to the brain, the sound in the form of nerve impulses and get it to the temporal cortex, which then decodes the nerve impulse perceived by the subject as sound.
What function does hearing serve?
Hearing is the sense in charge to pick up the sounds coming from outside the human body, and then to transmit them through a complex mechanism that originates in the ear, the temporal cortex, and the brain area that can receive these nerve impulses and decoded them in sounds understood by the subject.
