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How does the eardrum begin the process of hearing?

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Acoustics — acoustics Artificial omni-directional sound source in an anechoic acoustic chamber.

The eardrum, or tympanic membrane, initiates the process of hearing by acting as a mechanical receiver for sound waves directed through the outer ear.123

When airborne sound waves reach the eardrum, a portion of the sound is absorbed, causing the membrane to vibrate. The central portion of the membrane, known as the umbo, moves inward and outward like a stiff cone in response to these waves. The force and frequency of the incoming sound determine the intensity and speed of these vibrations.1

Because the tip of the malleus is attached to the umbo, the eardrum’s motion is directly transferred to the ossicular chain within the middle ear. This mechanical movement is crucial for overcoming the acoustic impedance mismatch between the air and the fluids of the inner ear, effectively acting as a transformer to amplify sound pressure before it reaches the cochlea.134