JOURNEY THROUGH THE EAR

PINNAE

• Soundwaves exist in environment
• Pinnae capture soundwaves
• Funnel into ear canal

Sound then travels through Ear Canal and vibrates the Eardrum.

Vibrations from eardrum continue down the ossicles, which are tiny bones leading to the cochlea.
Sound then passes to oval window, which de-amplifies it so it can enter the cochlea

COCHLEA

• Begins "Inner Ear"
• Site of transduction
• Fluid inside vibrates from oval window
• Cilia on Basillar Membrane
• Bending of hair cells creates impulse

One Sensory Unit is equal to the cilia and the nerve connected to it.

WAVELENGTH: creates the frequency or pitch of a noise.
AMPLITUDE: increases/decreases volume.

Helmholtz's Place Theory states that sound waves with different wavelengths go to different parts of the cochlea to be translated differently

Frequency Theory states that the different frequencies of the wavelengths cause impulses to be translated at different frequencies, causing the difference.

The Volley Principle says that pitch occurs due to the alternating firing of the neurons to create a more detailed picture

Regardless, the impulse travels from the cochlea to the Auditory nerve, and on to the brain.

IN THE BRAIN

• Impulse goes to both halves
• First enters Thalamus which-
• Relays signals to Cerebral Cortex-
• Temporal Lobe: Hearing Center
• Interprets as sound