Outer Hair Cells

Outer hair cells (OHCs) are a type of hair cell found in the cochlea, the hearing organ of the inner ear. OHCs are responsible for amplifying sound waves, which makes it possible for us to hear soft sounds.

What is the difference between inner and outer hair cells?

There are two main types of hair cells in the cochlea: inner hair cells (IHCs) and outer hair cells (OHCs). IHCs are the more numerous type of hair cell, and they are responsible for the transduction of sound waves into electrical signals that are sent to the brain. OHCs are much less numerous than IHCs, but they play an important role in amplifying sound waves.

What is the action of outer hair cells?

OHCs are able to amplify sound waves by a process called electromotility. Electromotility is the ability of a cell to change its shape in response to an electrical signal. When OHCs are depolarized, they contract. When they are hyperpolarized, they extend. This change in shape causes the basilar membrane, a thin membrane that runs through the cochlea, to vibrate more forcefully. This increased vibration is what allows us to hear soft sounds.

What is the function of the outer hair cells in the organ of Corti?

OHCs are located in the organ of Corti, which is a structure in the cochlea that contains the hair cells. The organ of Corti is also home to the tectorial membrane, a gelatinous membrane that sits above the hair cells. When sound waves enter the cochlea, they cause the basilar membrane to vibrate. This vibration, in turn, causes the tectorial membrane to vibrate. The vibrations of the tectorial membrane bend the hair cells, which sends an electrical signal to the brain.

How do the outer hair cells respond to sound?

OHCs respond to sound waves by changing their shape in response to the electrical signals that are generated by the hair cells. When sound waves are present, the hair cells are depolarized, which causes the OHCs to contract. This contraction causes the basilar membrane to vibrate more forcefully, which in turn increases the amplitude of the sound wave. This amplification of sound waves is essential for us to be able to hear soft sounds.


Outer hair cells are an essential part of the hearing system. They play a vital role in amplifying sound waves, which makes it possible for us to hear soft sounds. Without OHCs, we would not be able to hear as well as we do.