Auditory System Overview

The visible part of the ear that collects sound waves.

The tube connecting the outer ear to the middle ear, amplifying sound waves.

The thin membrane at the end of the auditory canal that vibrates in response to sound waves.

The region of the ear that amplifies sound waves through a chain of small bones.

The part of the ear that converts sound vibrations into electrical signals sent to the brain.

The loss of hearing ability, ranging from mild to severe.

A device used to test hearing by measuring sound perception at different frequencies.

The system composed of the ear, auditory nerve, and brain that processes sound information.

The tympanic membrane, also known as the eardrum, plays a crucial role in sound transmission. It acts as a thin, flexible membrane that vibrates in response to sound waves entering the ear canal. These vibrations are then transferred to the tiny bones of the middle ear, known as the ossicles.

When sound waves reach the tympanic membrane, they are partially reflected back into the ear canal and partially transmitted into the middle ear. This reflection and transmission are key to hearing sensitivity. The goal is to minimize reflection and maximize transmission for optimal hearing.

Impedance matching refers to the efficiency of sound transmission between different mediums. In the ear, a mismatch occurs between air (low impedance) and the fluid in the inner ear (high impedance). This mismatch leads to most of the sound energy being reflected back, resulting in a loss of hearing sensitivity.

The middle ear houses three tiny bones: the malleus (hammer), incus (anvil), and stapes (stirrup). These bones act as a lever system, amplifying sound pressure as it travels from the tympanic membrane to the oval window of the inner ear.

The middle ear's lever system provides a pressure amplification factor of approximately 22, meaning the pressure on the oval window is significantly higher than the pressure on the tympanic membrane. This amplification is achieved due to the difference in area between the eardrum and the oval window.

The middle ear also plays a role in filtering out unwanted noise generated by the body, like chewing or swallowing. This helps improve the clarity of external sounds. Additionally, the middle ear can adjust its vibration response to protect the inner ear from loud sounds, reducing the transmission of high-intensity vibrations.

The inner ear contains the cochlea, a snail-shaped structure responsible for converting sound vibrations into nerve impulses that the brain can interpret. The cochlea is filled with fluid and houses tiny hair cells that respond to vibrations, sending signals to the auditory nerve.

The inner ear is further divided into three chambers filled with fluid: the vestibular chamber, the middle chamber, and the tympanic chamber. These chambers are separated by membranes, including the Reissner membrane and the Basilar membrane.