Hearing is the ability to hear sounds.
Hearing can be studied from the point of view of physiology, and the focus will then be on the functioning of the ear, external and internal, which is the organ most involved in hearing.
The ear is the organ that captures sound and is therefore the seat of the sense of hearing, but it also plays an important role in balance. In common parlance, this word often refers to its outer, highly visible part, the pinna. It also applies to the entire system, the hearing aid, both external and internal, which collects and understands sounds. Only vertebrates have ears, but many invertebrates are able to perceive sounds using other senses.
From a medical point of view, we are interested in hearing defects that patients may complain about (difficulties in hearing sounds). In order to detect these problems by early examinations, normal hearing is defined. Hearing loss can be bilateral or unilateral (only one ear affected), transient or permanent, more or less important depending on the case.
The causes of hearing loss can be age-related (decrease in normal hearing acuity as we age, also known as presbycusis), infectious, traumatic or environmental (work or activity in a noisy environment). The differences range from presbycusis to deafness (when no sound is perceived). However, in some people, hearing loss or deafness occurs suddenly.