How do we hear?
At the heart of our auditory system are intricate hair cells nestled within the human cochlea.
Each cochlea houses around 16,000 of these flask-shaped sensory cells, each with a cluster of hair-like projections called stereocilia.
These stereocilia, arranged like a staircase from the shortest to the tallest, are the key to our hearing.
Two adjacent stereocilia are connected by a filamentous extracellular tether called a tip link.
These tip links, functioning like a complex network of connections, are pivotal in our hearing process, converting sound waves into electrical signals our brain can interpret.
When sound waves reach the ear, they create vibrations in the inner ear fluid.
These vibrations cause the stereocilia to bend, stretching the tip links that connect them.
This stretching opens ion channels in the stereocilia that allow potassium ions to enter the hair cell and create an electrical signal.
Nerve cells attached to the hair cells pick up this signal and send it to the brain, where it is interpreted as sound.
This mechanism is similar to a microphone converting sound waves into electrical signals.
Frequency range
Humans can perceive sound in the range of 20 Hz to 20 kHz in frequency and 5-120 decibels (dB) in intensity.
These sounds produce a force of 10–100 piconewtons (pN) on tip links
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