What occurs when hair cell damage in the cochlea leads to a permanent loss of hearing?

When hair cell damage in the cochlea occurs, it disrupts the normal functioning of the auditory system. Hair cells are essential for converting sound vibrations into electrical signals that the brain interprets as sound. When these cells are damaged, the ability to perceive sound diminishes, resulting in a condition known as a permanent threshold shift. This means that the minimum level of sound that can be heard is permanently elevated, indicating a lasting reduction in hearing sensitivity.

In contrast, temporary threshold shift refers to a temporary decrease in hearing sensitivity that often recovers following exposure to loud sounds. Acoustic trauma describes specific incidents of sudden hearing loss due to extremely loud sounds, but it does not necessarily imply lasting damage unless there is hair cell destruction. Auditory fatigue refers to a temporary reduction in hearing perception after prolonged exposure to sound, which also resolves over time and does not indicate any permanent loss. Thus, permanent threshold shift accurately characterizes the long-lasting impact of hair cell damage in the cochlea.