How do Humans Hear

The human ear, although is not much to look at, but it is an excellent masterpiece of engineering, which makes hearing possible. Hearing is a combined effort of the structure of the outer ear, middle ear and the inner ear. So, in order to understand the concept behind hearing, it is important to know about the working of the human ear. Let's try to understand, how do humans hear?

The Ear
As mentioned earlier, the human ear consists of the outer, middle and the inner ear. Each structure contributes to the hearing, with their specific working mechanisms. They perform different functions for converting sound waves or vibrations into nerve signals that can be interpreted by the brain as meaningful information.

The Outer Ear
The outer ear is the external and the visible portion of the ear. It performs the simplest functions in the process of hearing. The outer ear is boneless and consists of the pinna or auricle (the visible projection portion of the ear) and an 'S' shaped tube, the external auditory or acoustic meatus (the outside opening to the ear canal). The sound waves that are generated by a source, when reach our ear, are collected by the outer ear and channelized through the ear canal to the eardrum. The eardrum, also known as the tympanic membrane, is a thin sensitive membrane that is stretched tightly over the entrance to the middle ear.

The Middle Ear
The middle ear comprises the tympanic membrane (eardrum) and the ossicles or bones. The ossicles are the malleus or hammer, the incus or anvil and the stapes or stirrup. After the sound waves hit the eardrum, pressure difference created by the sound waves causes the eardrum to vibrate in a to and fro motion. This vibration is passed on to the hammer, whose one end is attached to the eardrum and the other end to the anvil. The hammer then causes the anvil to vibrate. The anvil is again attached to one end of the stirrup, and it's vibration causes the stirrup to vibrate. Being the smallest bone, the stirrup fits into the oval window (fenestra ovalis) between the middle and the inner ear.

The Inner Ear
The vibrations via the oval window sets the watery fluids in the cochlea into vibratory motion. The cochlea is an essential organ of hearing; auditory portion of the ear. The pressure waves in the fluid, caused due to the vibrations, sets thousands of specialized cells with microscopic hair-like nerve endings into vibration. This vibration of these hair cells is known as mechanotransduction. This phenomenon enables the cells to transmit the vibrations-turned-electrical signals to the neurons or nerve cells. These neurons pass the signals through the auditory nerve to the auditory cortex (hearing center) of the brain. This is where the brain interprets the signals and recognize them as information or different types of sound. Inshort, the concept of hearing is implemented.

To conclude, the answer to question as how do humans hear, lies in the working of the different sections of the ear. Sound travels at a speed of 340.29 m/s and the process which enables us to hear any sound, takes place within a fraction of second. So, you can imagine the amazing work that is carried out by the human ear. For all of us, hearing is just like any other simple function of the human body. However, the whole process that goes into the concept of hearing is far from being just simple and describable in words.