How does the brain distinguish between low-pitch and high-pitch sounds?

The brain distinguishes between low-pitch and high-pitch sounds by detecting the frequency of sound waves. Sound waves are characterized by their amplitude (loudness) and frequency (pitch). The frequency of a sound wave determines its pitch, with low-frequency sound waves producing low-pitch sounds and high-frequency sound waves producing high-pitch sounds.

When a sound wave enters the ear, it travels through the ear canal and causes the eardrum to vibrate. The eardrum transmits these vibrations to the middle ear, where the malleus, incus, and stapes amplify the sound and send it to the inner ear.

In the inner ear, the sound waves enter a coiled structure called the cochlea, which is filled with fluid. The cochlea is lined with hair cells that act as sound receptors. These hair cells are tuned to different frequencies, with some cells responding to low frequencies and others responding to high frequencies.

When sound waves enter the cochlea, they cause the fluid to vibrate, which in turn causes the hair cells to move. The hair cells then convert these mechanical vibrations into electrical signals that are sent to the brain through the auditory nerve.

The brain interprets the frequency of the sound wave based on the pattern of electrical signals that it receives from the auditory nerve. Sounds with low frequencies produce a slower pattern of electrical signals, while sounds with high frequencies produce a faster pattern of electrical signals. This allows the brain to distinguish between low-pitch and high-pitch sounds.

In addition to frequency, the brain also uses other factors such as timbre, loudness, and duration to distinguish between different sounds.