Auditory signals are processed in the human brain through a complex auditory pathway that involves several key brain structures.

The journey of auditory signal processing begins with the detection of sound waves by the ear. The outer ear captures these sound waves and funnels them into the ear canal, where they strike the eardrum, causing it to vibrate. These vibrations are then transmitted to three small bones in the middle ear: the malleus, incus, and stapes. The stapes bone exerts pressure on the oval window of the cochlea, which is a fluid-filled structure in the inner ear. This action creates fluid waves that stimulate hair cells within the cochlea.

The hair cells, located on the basilar membrane of the cochlea, play a crucial role by converting mechanical vibrations into electrical signals through a process known as mechanotransduction. These hair cells are arranged in a tonotopic manner, meaning that different sound frequencies stimulate specific regions of the cochlea. High frequencies activate the base of the cochlea, while low frequencies activate the apex.

Once the hair cells generate electrical signals, these signals are transmitted to the brain via the auditory nerve, also referred to as the cochlear nerve. This nerve carries the signals to the cochlear nucleus, located in the brainstem, which serves as the first central processing center for the auditory system. From the cochlear nucleus, the signals are relayed to the superior olivary complex, which aids in sound localization by comparing the timing and intensity of signals received from both ears.

The auditory signals then proceed to the inferior colliculus, which integrates auditory information with inputs from other sensory modalities. Subsequently, the signals travel to the medial geniculate nucleus of the thalamus. The thalamus functions as a relay station, forwarding the signals to the primary auditory cortex located in the temporal lobe of the brain.

In the primary auditory cortex, the signals are processed and interpreted as distinct sounds. This region of the brain is also organized tonotopically, reflecting the arrangement of hair cells in the cochlea. This organization enables us to perceive and differentiate between various pitches and volumes of sound. Furthermore, the auditory cortex interacts with other brain areas, such as the frontal lobe, allowing us to associate sounds with memories and emotions.