Considered a paramount sense for humans, hearing facilitates communication by receiving sounds and interpreting speech.
Sound waves are captured by the external ear, comprising the pinna and the external auditory canal, and directed to the tympanic membrane (eardrum) for vibration. Linked to the tympanic membrane, the malleus (hammer) transmits vibrations to the incus (anvil), which then passes them to the stapes (stirrup). Hair cells convert mechanical vibrations into electrical signals, stimulating the 30,000 fibers of the auditory nerve. These signals travel to the brainstem, then to the auditory cortex responsible for sound perception.
Hearing provides essential survival cues, like alerting us to oncoming vehicles to avoid danger.
Similar to the visual system, our auditory system discerns various attributes in detected signals, such as location, loudness, and pitch. Unlike the visual system, which blends different light wavelengths for color perception, the auditory system separates complex sounds into component tones or frequencies, allowing us to distinguish voices or instruments in conversations or music.
From the chirp of crickets to the roar of a rocket engine, sound waves are captured by the external ear, funneled to the tympanic membrane, and then transmitted through the middle ear’s chain of bones to the fluid-filled inner ear. There, pressure waves in the cochlea, a snail-shaped structure, stimulate hair cells atop the basilar membrane, converting vibrations into electrical signals that excite the auditory nerve fibers.
In the auditory cortex, neighboring neurons specialize in responding to tones of similar frequencies but may differ in tone combinations they recognize. Some neurons respond to pure tones, others to complex sounds, and some to variations in sound duration or frequency. Information from these neurons combines to recognize words or instruments.
Sound processing occurs in various regions of both brain hemispheres, with the left side typically specialized for speech perception and production. Damage to the left auditory cortex, such as from a stroke, can result in the inability to comprehend language despite intact hearing.
REFERENCES
https://www.brainfacts.org/thinking-sensing-and-behaving/hearing/2012/hearing