Ear
The ear was part of a sensory system found in most carbon-based lifeforms, typically, but not always, consisting of a fleshy outer appendage usually called the outer ear, as well as a group of canals and vibration-sensitive membranes and small bones located inside the skull. Ears functioned by receiving vibrations in the ambient atmosphere and translating them into electrical impulses sent to the brain, which allowed a humanoid to "hear" sounds around them.

Most humanoid species' ears were located on or around the outer areas of the skull, and the sensitivity and range of sounds audible varied greatly among species. The three bones of the Human middle ear were the malleus, incus, and stapes. The ear also had a tympanic membrane, which was the connective tissue between the middle and external auditory canal. ()

Human ears were typically mostly round, fleshy appendages, while Vulcan ears were more typically pointed at the top. These features made Vulcans the frequent subjects of ridicule by Humans, although the stoic Vulcans were confounded by Human "fascination" with their ears. The shape of Vulcan ears was a result of many millennia of evolution; however, it did not give them superior hearing to that of other, similar humanoid species without pointed ears. ()

The Ferengi had large, rounded ears, the rims of which they referred to as "lobes". Physically, the lobes were highly sensitive areas that produced feelings of pleasure and contentment when stroked, as in the technique called oo-mox. However, the lobes were also very sensitive to pain. () In 2369, while under the influence of the Saltah'na energy spheres, Major Kira Nerys proposed that Constable Odo support her in her "mutiny". If he would do so, she offered him full authority on how to handle the martial law on the Promenade, and even to be able to toss Quark out of the station – on his ears. ()

In July of 2151, Sub-Commander T'Pol hid her Vulcan ears under a long-haired wig while on a covert mission on the Akaali homeworld. ()

In late 2369, Vedek Bareil Antos told Commander Benjamin Sisko that, when he was five years old, he knew a monk who could "squeeze the pagh right out of your ear with his thumb and forefinger". ()

Many species such as the Gorn had no external appendage or visible "ear" but could hear as well as, and in some cases far better than, species with external auditory organs. ()

The Soong-type androids' ears were fully integrated and were not removable. () They also had a sensitivity greater than those of the average Earth dog. ()

In 2374, Lieutenant Commander Jadzia Dax, a Trill, asserted that she preferred spots to pointed ears in response to Captain Benjamin Sisko's comment that she would have made a good Romulan. ()

Sensitivity 
The sensitivity and hearing ranges for species varied widely, even on the same planet. Vulcan hearing was known to be more acute than that of most Humans. Ferengi had extremely sensitive hearing as well. Vorta were genetically engineered with no aesthetic sense, but had acute hearing, as Weyoun was able to hear Gul Dukat's quiet discussion about his daughter with his subordinate Damar. ()

Shalaft's Syndrome was a genetic disorder which caused an extreme sensitivity to sound; this condition was suffered by both Captain Jean-Luc Picard and his clone Shinzon. ()

In 2258 of the alternate reality, while attempting to change her assignment from the  to the ,   reminded  of her "exceptional aural sensitivity", a fact which the latter did not dispute. ()

Deafness 
The state of being unable to hear, whether by genetic makeup, congenital defect, or external damage to a being's hearing, was known as deafness. Some societies considered deafness a weakness or handicap, while others had no social stigma attached to it. ()

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Anatomy