How Do We Hear?

Overview

• Hearing Process: Converts sound waves into electrical signals.
• Pathway: Auditory nerve carries signals to the brain.
• Resources: Animated video available - Journey of Sound to the Brain.

Anatomy of the Ear

• Outer Ear: Includes pinna, temporal bone, and ear canal.
• Middle Ear: Contains eardrum and tiny bones (malleus, incus, stapes).
• Inner Ear: Comprises semicircular canals, Eustachian tube, cochlea, vestibule, and auditory nerves.

Hearing Steps

1. Sound Waves Entry:
   • Sound enters through the outer ear, travels through ear canal to the eardrum.
2. Vibration Transmission:
   • Eardrum vibrates, sending vibrations to middle ear bones (malleus, incus, stapes).
3. Sound Amplification:
   • Middle ear bones amplify sound vibrations and send to cochlea in inner ear.
4. Cochlea Function:
   • Cochlea has fluid and a basilar membrane that splits it. Vibrations create a wave.
5. Hair Cells Activation:
   • Hair cells on basilar membrane detect sound frequencies (high pitch at cochlea's wide end, low pitch near center).
6. Electrical Signal Creation:
   • Movement of hair cells opens channels, allowing chemicals to create an electrical signal.
7. Signal Transmission:
   • Auditory nerve carries electrical signal to the brain, translating it into recognizable sound.

Additional Information

• Contact: NIDCD Information Clearinghouse, Bethesda, MD.
• Communication: Phone, TTY, and email options available.

Updates

• Document Last Updated: March 16, 2022.

News Highlights

• Challenges in hearing in noisy environments, genetic causes of hearing loss, and brain's processing of speech melody.

Resources

• Languages: Available in English and Spanish.
• Publications: Free publications and PDFs available.
• Contact: Questions can be directed to NIDCD through various communication methods.