Chapter 9: Hearing

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Soundwaves

Vibrations in the air that our ears detect and the brain interprets as sound.

Frequency

Determines pitch (how high or low a sound is).

Amplitude

Determines loudness (how soft or loud a sound is).

Complexity / Waveform (Timbre)

Determines timbre or uniqueness (why a piano and guitar sound different).

Pinna

The outer ear that collects sound waves.

External Ear Canal

Channel that directs sound to the eardrum.

Eardrum (Tympanic Membrane)

Vibrates when sound waves hit it.

Ossicles

Three tiny bones that amplify sound vibrations.

Cochlea

Fluid-filled structure that converts vibrations into neural signals.

Organ of Corti

Structure inside the cochlea that contains hair cells.

Basilar Membrane

Vibrates in response to different sound frequencies.

Tectorial Membrane

Helps bend hair cells during sound processing.

Hair Cells

Convert sound vibrations into neural signals.

Stereocilia

Tiny hair-like structures that move and trigger neural signals.

Tonotopic Organization

Different sound frequencies are processed in different locations along the cochlea and auditory cortex.

Anterior Auditory Pathway

Involves the prefrontal cortex; helps identify what the sound is.

Posterior Auditory Pathway.

Involves the parietal lobe; helps identify where the sound is coming from.

General Auditory Pathway

Medulla, Tectum, MGN, Primary Auditory Cortex.

Medulla

First brainstem relay for auditory signals.

Tectum

Involved in auditory reflexes.

MGN (Medial Geniculate Nucleus)

Thalamic relay station for hearing.

Primary Auditory Cortex

Located in the temporal lobe; processes sound information.