How the Brain Works The Facts Visually Explained by DK (z-lib.org)

BRAIN FUNCTIONS AND THE SENSES

Perceiving Sound

Inside the auditory cortex

Signals from the thalamus (see p.75) are sent to

the primary auditory cortex, which is divided into

sections that respond to a range of frequencies.

Some of these sections focus on intensity rather

than frequency, while others pick up more complex

and distinctive sounds, such as whistles, bangs, or

animal noises. Signals then pass to the secondary

auditory cortex, which is thought to focus on

harmony, rhythm, and melody. The tertiary auditory

cortex integrates all the signals to give an overall

impression of the sounds picked up by the ears.

The auditory cortex

The auditory cortex is the main

processing center for sound. It is

located in the temporal lobe, just below

the temples on either side of the head.

The cochlea

Areas along the curl of the cochlea respond

to different frequencies of sound, from

high-pitched at the apex to low bass

notes at the base. These are mirrored by

corresponding areas in the auditory cortex.

Perceiving Sound

Every sound is made up of a number of different

components. The brain has to take all the details

of its frequencies, intensity, and rhythm to

process, identify, and remember the sound.

This area receives

signals from low-

frequency sounds

Corresponds to

apex of cochlea

Receives signals from

high-frequency sounds

Corresponds to

base of cochlea

Primary auditory cortex

identifies frequency and

intensity of sounds

Secondary auditory cortex

interprets complicated

sounds, such as language

Base of cochlea

transmits low-

frequency sounds

Tertiary auditory cortex

integrates hearing with

other sensory systems

Apex of cochlea

transmits high-

frequency sounds

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More flexible part

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Organ of Corti is main

organ of hearing

Row of

hair cells

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