Tiny hair cells inside the cochlea convert vibrations into electrical signals the brain can read.

The longer version

Inside the coiled inner ear, a travelling wave rolls along a flexible membrane, and bundles of microscopic hairs riding on it bend with the motion. Bending opens ion channels, generating an electrical change that triggers fibres of the auditory nerve, which carry a coded report to the brain.

Place along that membrane maps to frequency, with one end responding to low vibrations and the other to high ones, so the ear performs a kind of mechanical spectrum analysis before any thinking happens. Different groups of hairs also handle different intensities. Loud exposure tires the high end first, which is why hearing loss often shows up there.

Where this entry sits

Sound and Music gathers facts about how vibrations move through air and water, how ears turn them into meaning, and how instruments and notation shape what listeners hear. Expect echoes, pitch, volume, acoustics, and the odd silence in between. The full list sits on the Sound and Music page, where every entry is listed in order.