How Sound Works: Ear Vibrations and Hearing Explained

There is no vibrating “canal” inside the ear. Hearing is a transduction process converting sound waves into neural signals.

The Pathway

1. Outer ear (pinna + ear canal): Collects and funnels sound waves.
2. Tympanic membrane (eardrum): Vibrates in response to pressure waves.
3. Middle ear (ossicles): Malleus, incus, stapes amplify vibrations (~20×) and transmit to oval window.
4. Inner ear (cochlea): Fluid-filled scalae; stapes motion creates traveling wave on basilar membrane.
5. Hair cells: Inner hair cells (transducers) deflect → mechanotransduction → glutamate release → auditory nerve (CN VIII) firing.
6. Central pathways: Brainstem → thalamus → auditory cortex → perception.

Key Points

• Frequency coding: base (high pitch) → apex (low pitch) – tonotopic map.
• Outer hair cells amplify (cochlear amplifier) – active process, vulnerable to noise/ototoxins.
• No “vibrating canal” – the ear canal is a passive conduit; vibration occurs at the eardrum and basilar membrane.