Sound is one of the five basic senses. The hearing process is complex and consists in the registration of sound from the environment and its interpretation of the meaning. To understand how we hear, we need to know from how the ear and the auditory pathway.

The introduction can be divided into three parts, the outer, middle and inner ear. Outer ear consists of the external auditory hall and eardrum. Sound (mechanical) wave travels to the eardrum which moves its mechanical power. The middle ear is located behind the eardrum and includes, among other things, a chain of ossicles. The chain is linked in part to the eardrum, and the other for the cochlea and inner ear. Ossicles further by launching its vibrations are transmitted by starting fluid in the inner ear. This causes movement of ciliated cells in the organ of Corti of the cochlea. Generate electrical signals that are transmitted auditory nerve and continue through to the cortical auditory centers in the brain, which interprets electrical signals as sound.
Hearing impairment, depending on who is part of the auditory times damaged, can be divided into conductive (conductive), sensorineural and mixed hearing loss.

Conductive hearing loss occurs when sound is not transmitted efficiently through the outer drought corridor, through the eardrum and ossicles to the inner ear. Reduced registration is quieter sound. Usually it is a transient hearing impairments that can be treated. Possible causes of conductive hearing loss infection of the middle ear (otitis media), lag secretions in the middle ear after an infection or allergy (secretory otitis), dysfunction of the Eustachian tube, the greater the amount of wax in the external auditory canal (cerumen), inflammation of the skin spoljašjeg ear canal (otitis externa), a foreign body in the external auditory canal, tympanic membrane perforation, tumors and malformations of the external and middle ear.
Sensorineural hearing loss is caused by damage to the inner ear (cochlea), auditory nerve or in other parts of the auditory times. Reduced the ability of registering sound; Even if the sound is strong enough, it may be unclear. This is the most common type of permanent hearing damage. In most cases can not be resolved surgically. Common causes of sensorineural hearing loss is aging, the use of ototoxic drugs, noise, genetic factors, head trauma, inner ear malformations and other diseases.
A mixed hearing loss implies the existence of a combination of conductive and sensorineural hearing loss.