There are certain reasons, biological or environmental, responsible to cause permanent hearing loss. It’s a partial or total inability of 
ears to perceive sound waves. Hearing loss can be transitory or permanent; with the use of medications and surgical methods, temporary hearing loss can be treated. While permanent hearing loss is incurable.
Type of hearing loss is determined by the affected part of ear.
The most common causes of permanent hearing loss include:
Age Factor: Changes in the nerves and cells occurs as one gets older, result in gradual but steady hearing loss called age-related hearing loss. Whether it’s mild or severe, it is always permanent in nature.
Noise: exposure to noise while working, during reaction (like riding motorcycles), or even doing common chores of routine life can lead to Noise-induced hearing loss. It develops gradually over many years and can affect individuals of all age groups.
Some other causes of hearing loss may involve:
Ear Infection: infection in the middle ear (otitis media) or in the ear canal (otitis externa or swimmer’s ear) lead towards permanent hearing loss.
Otosclerosis: it is the state, when the bones of the middle ear are affected.
Seepage of Fluid: After a cold or flu or traveling in an airplane, the seepage of fluid in the middle ear can also cause hearing loss.
Earwax: sometimes the build up of ear wax can cause hearing loss.
Injury to the Ear or Head: Some injuries to the head or ears damage the structure in the ear which results in sudden hearing loss.
Meniere’s Disease: temporary or permanent hearing loss may be developed in the consequences of Minere’s disease.
Ototoxic Medicines: overuse of certain antibiotics like salicylates, aminoglycoside and chemotherapy drugs can bring hearing loss.
Trauma: the puncture of the eardrum with the use of foreign objects and temporal bone fracture results in the trauma of hearing loss.
Acoustic Neuroma: the development of a non cancerous tumor on the nerve which helps in hearing may bring hearing loss.
Sometimes the growth of non cancerous benign in the ear canal, like osteomas, exostoses and glomus tumors can cause hearing loss by blocking the ear canal.
A major reason of permanent hearing loss is the use of antibiotics in premature babies particularly those who have an inherited sensitivity towards antibiotics.
In addition to the above, there may be other reasons which may indirectly lead towards permanent hearing loss.
