How our ear functions and how brain receives and perceives sound impulses hold the key to better understanding of hearing and hearing loss. The process of hearing starts with a properly functional outer ear that collects the sound waves emitted from a source and passes it through ear canal to the eardrum. The impact of sound waves on the eardrum creates vibration, which further results in movement of three bones located in the middle ear. The movement of the bones, especially of stapes, which is also the smallest of the three, results in vibration of the oval window situated between middle and the inner ear. This vibration impacts the fluid in the inner ear which further transmits the signals to cochlea, the organ which is responsible for hearing.
The vibration of the fluid inside the inner ear bends the hair cells that act as receptors. The bending of these cells triggers impulses that are transmitted to the brain through auditory nerves. Brain on receiving the impulse translates into the sound and comprehends it for further processes.
The problem of hearing loss, if not since birth, is often a like a process than an occurrence. Other than due to accidental reasons, when the loss can be instantaneous, normally it is caused over a prolonged period of time. In the beginning the hearing loss can be deceptive; however, with time, it goes profound and start interfering with your ability to react to a sound and thus becomes prominent during conversational speech.
Conductive hearing loss:This type of hearing loss is directly associated with inability of or malfunctioning of outer or middle ear. In this condition, either outer ear or middle ear or both, fails to collect and carry forward the sound waves emitted from a source. This condition, in most of the cases is treatable; however, the method of treatment depends upon the actual problem. In maximum cases of conductive hearing loss, depositions of wax in the ear canal or fluid build up behind the eardrum are the prime reasons. However, in some of the cases, it is also caused due to disrupted bones of the middle ear or due to disrupted ear drums.
Sensory hearing loss:Deformity of Cochlea, degeneration of inner air due to aging, infection, meniers disease, exposure to excessive noise and genetic syndrome are the main reasons that cause sensory hearing loss. The treatment procedure of this condition is not easily possible either through medicine or surgery.
Neural hearing loss: If there is considerable damage of hearing nerves or the part of nervous system that is responsible for hearing has been damaged then such cases fall under the category of neural hearing loss.
Mixed Hearing Loss:When a person is suffering from conditions like Otosclerosis then it causes damage to both middle and inner ear and also to the neural system of ear. Such patients are said to be suffering from mixed hearing loss.
Age : Age related degeneration of middle ear, inner ear and nerves that are responsible for hearing are main cause of hearing loss.
Disease :Measles, mumps or any other such type of viral infection, along with diseases like Meniere's syndrome, tumors of the hearing nerve and meningitis are the second largest reason for hearing loss.
Drugs :There are certain drugs that are known to hamper the functionality of hair cells present in the inner ear; causing hearing loss. Quinine, aminoglycosides, aspirin are some of such drugs that can trigger hearing loss.
Infections :Otitis media is a condition that causes formation of fluid in the middle ear. This fluid hampers hearing to a great extent and can be triggered due to sore throat and inflamed tonsils.
Malformation :If the outer ear or the ear canal is malformed; then it causes acute hearing loss.
Noise : Excessive noise pollution or if exposed to loud noise for a long period of time, then such exposure can cause permanent hearing loss.
Perforation : Drastic change in the air pressure over the eardrums in comparison to the air pressure maintained in the inner ear; such as during adventure sports like paragliding or scuba diving; there are chances of perforation of eardrums, resulting in hearing loss.
Wax : Ear canal, if is blocked due to Wax buildup, then it stops sound to travel towards the inner ear and thus can also cause hearing loss. However, such type of hearing loss can be easily treated with proper medical attention and personal hygiene.