The worsening of hearing ability is the subject of many detailed studies; research to date has indicated several factors that contribute to partial or total loss of hearing.

Age
Throughout the world, statistics reveal that the process of human ageing is definitely one of the most important causes of some kind of hearing deficit. A high percentage, about 30%, of the population aged over 65 suffer and it appears to be one of the most common complaints among elderly people. 

Noise
Noise, on the other hand, is the primary cause of professional invalidity. The deafening background noise of daily life is not only irritating, it causes damage. Not only is hearing affected but the whole body suffers with serious consequences such as increased blood pressure, tachycardia, arrhythmia, heartburn, muscular tension, intestinal problems, and so on.

Heredity
About one third of hearing difficulties present at birth are caused by hereditary factors. One gene has been indicated as responsible for this: connexion 26. If there are cases of hypoacusis in the family, there is a high probability that this will be transmitted to the children. If two hard-of-hearing people get married, it is advisable to consult an audiologist or a geneticist, a specialist in hereditary illnesses.

Infections
Several bacterial and viral illnesses (scarlet fever, rubella, meningitis and others) can damage the ear and cause some degree of hearing loss. Otitis, a common illness among young children, can cause irreversible hypoacusis if not treated in time.

Otosclerosis
This is an illness that affects the mobility of the small bones in the middle ear. The vibrations transmitted to the inner ear no longer have the same regularity as those in a healthy ear and so hearing efficiency is reduced.

Medicines, alcohol, smoking
It has been shown that some medicines and some substances such as alcohol and nicotine can be harmful to the ear and are defined as ototoxic i.e. toxic for hearing.