Startle Reflex

An inherent, involuntary response to sudden or loud noise in which the neck and limbs are recoiled towards the chest. It is enhanced in individuals with high anxiety. See also heebie-jeebies.

Reference:

Westman, J. C., & Walters, J. R. (1981). Noise and stress: a comprehensive approach. Environmental Health Perspectives, 41, 291. https://doi.org/10.1289/ehp.8141291