MODULE 2 OF 6

The Ear & Hearing

Anatomy of hearing, from outer ear to cochlea, and how we perceive sound spatially.

Anatomy of the Ear

Outer Ear: The pinna collects sound; the ear canal amplifies frequencies around 3 kHz (crucial for speech).

Middle Ear: The eardrum and ossicles amplify pressure ~20× for the air-to-fluid transition.

Inner Ear: The cochlea's ~15,000 hair cells convert vibrations to neural signals, arranged by frequency.

Interaural Time Difference (ITD): Sound reaches the closer ear first. We detect differences as small as 10 microseconds.

Interaural Level Difference (ILD): The head creates an acoustic shadow, making sounds quieter at the far ear.

Hair cells don't regenerate. Sounds above 85 dB cause cumulative damage. At 100 dB, damage occurs within 15 minutes. Always use hearing protection.