Britannica Sources used in this answer

How do mammals protect their ears during a startle reflex?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A fluffy gray cat clings to the trunk of a tree, looking upward as it climbs to escape. — Avoidance behaviour Cat fleeing by upward climbing.

During a startle reflex, mammals employ both external and internal mechanisms to protect their ears from potential harm.

Externally, many mammals exhibit a protective reflex involving ear retraction, where the ears are pulled back against and slightly behind the skull to a position of safety. In some species, such as the bush baby (Galagos), the outer ear can fold both laterally and longitudinally under threat.1

Internally, mammals utilize a reflex involving the muscles of the middle ear—the tensor tympani and the stapedius. In response to high-intensity sounds, these muscles contract to add friction and stiffness to the ossicular chain. This action reduces the mobility of the ossicles, thereby decreasing the intensity of sound transmitted to the inner ear. However, because these middle-ear muscle contractions are not instantaneous and fatigue quickly, they provide limited protection against sudden, extremely loud noises like explosions.23