These hillocks develop into the folds of the auricle and gradually shift upwards and backwards to their final position on the head.

The final three hillocks are derived from the second branchial arch and form the antihelix, antitragus, and lobule, respectively.

This explains why vesicles are classically seen on the auricle in herpes infections of the facial nerve (Ramsay Hunt syndrome type II).

This amplification is an important factor in inner ear trauma resulting from elevated sound levels.

Non-electrical hearing apparatuses which were designed to protect hearing (particularly that of musicians and others who work in loud environments) which fit snugly in the concha have been studied by the Institute of Sound and Vibration Research (ISVR) at the University of Southampton in the U.K. [3] Due to its anatomy, the pinna largely eliminates a small segment of the frequency spectrum; this band is called the pinna notch.

For low frequencies, it behaves similarly to a reflector dish, directing sounds toward the ear canal.

External pinnae are absent in other tetrapod groups such as reptiles, amphibians, and birds.