Recording-2025-02-11T17:39:24.329Z

Anatomy of the Ear

• Tympanic Membrane: Vibrations are transmitted through the ear canal to the tympanic membrane.

• Middle Ear: Contains three bones (ossicles) that transmit vibrations to the cochlea.

• Cochlea: A spiral-shaped structure filled with fluid; contains hair cells that act as receptors for sound.

Processing of Sound

• Transmission to Cochlea:

  • The stapes connects to the cochlea via the oval window.

  • Vibrations from the stapes cause fluid in the cochlea to vibrate.

  • Hair cells along the cochlea detect these vibrations and convert them to nerve signals.

• Mechanoreceptors: Hair cells are specialized cells that respond to fluid movements and vibrations.

Structure of Flow in Cochlea

• Organ of Corti: Located within the cochlea, houses the hair cells that detect sound vibrations.

• Stereocilia: Tiny hair-like projections on hair cells that respond to fluid movement by opening potassium channels.

• Signal Transmission:

  • When fluid moves, stereocilia bend and open ion channels.

  • This leads to the depolarization of hair cells and the release of neurotransmitter glutamate.

Frequency and Pitch Determination

• Role of Cochlear Structure:

  • Cochlea has regions sensitive to different frequencies (higher frequencies near the base; lower frequencies towards the apex).

  • The brain interprets frequency based on the location of activated hair cells along the cochlea.

• Loudness Perception:

  • The rate at which hair cells fire determines the perceived volume (rapid firing for loud sounds, slower for quiet).

Signal Pathway to the Brain

• Cochlear Nerve: Transmits auditory information to the brainstem.

• Neural Processing: Information is relayed to the thalamus and then to the auditory cortex for interpretation.