General / Human Biology

Ears and their function

Human ear

I hear so many wonderful bird calls every morning nowadays which I hardly noticed before. Staying at home for nearly a year has not just opened my mind to new experiences of the natural world, it has opened my ears as well. So what are these ears? Coming to think of it, human ears have a weird structure which protrudes out of our body but not in an obvious way. Are ears used only for hearing, is there any other use for them? Human ears are made of an external ear called Pinna, external auditory tube, ear drum, middle ear and inner ear. When vertebrates evolved from aquatic organisms to terrestrial organisms, they had to change their ear anatomy to adapt to sounds that traveled through air resulting in the development of the middle ear. 

Ear and it’s auditory system is a remarkable part of our body as it combines multiple steps of processing the sounds we hear. This remarkable system helps us become aware of the environment around us, almost a 360 degree awareness. The system allows us to hear, differentiate various frequencies, and help us locate the source/direction of the sound to name a few. Additionally, in humans, ears also assist in maintaining posture, balance, locomotion of the body and gaze (stare) stabilization. Thus playing a major role in both verbal and non verbal communication. In the 15th century itself, the presence of ear drums and some of the bones involved in the making of inner ear was discovered. 

Elephant ears

Audible communication can be divided into 2 parts: short range communication and long range communication. We humans have limited long range communication as our ears have not evolved to hear sounds from distant places which of course we have overcome by inventing phones, however other animals have relied on evolution of their anatomical parts to overcome challenges of long distance communication. In elephants, long distance communication with other herds is done using infrasonic (low frequency) vocalizations which are below our audible range (below 20 Hz). Elephants can hear these low frequency sounds from as far as 1-2kms. There are many such examples in the natural world of animals which can hear sounds which are beyond human hearing range. 

Ear thermometer

On one side, nature gave us ears to hear sounds and possibly save ourselves from dangers, on the other hand we humans have found a clever use of ears which doesn’t involve hearing which involves measuring core body temperature (CBT). Benzinger et al. showed that tympanic membrane (also known as the eardrum)   can be used to measure CBT accurately in their research conducted in 1959. He hypothesized that as eardrum is close to hypothalamus and internal carotid artery, this might be the most ideal candidate to measure CBT. This and further research this led to a device called ear thermometers which are commonly used to check for fevers especially in young children. 

Researching for this article has shed light on ears and hearing which I wasn’t aware of before giving me a new appreciation for both nature and technology.

Royalty free images were used for this article.

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