BioPsy: Finals L2.2 - Audition

Audition

The sense of hearing

Ear

It is divided into three parts: Outer, Middle, and Inner Ear.

Outer Ear

• Pinna

• External Auditory Canal

• Tympanic Membrane

Middle Ear

• Ossicles

• Eustachian Tube

Ossicles

Three small bones that are connected and transmit the soundwaves to the inner ear.

Eustachian Tubes

A canal that links the middle ear to with back of the nose.

Inner Ear

• Cochlea

• Vestibule

• Semicircular Canals

Cochlea

• The nerves for hearing.

• We rely on this part of the inner ear for distinguishing the different frequencies we hear.

  • Bass (Low Frequency)

  • Bees (High Frequency)

• Converts the sound to a neural impulse that eventually reaches the brain.

Vestibule

The receptors for balance.

Semicircular canals

Similar to vestibule, this part of the inner ear also have receptors for balance.

Auditory Sensory Processing

How the cochlea distinguishes between sounds of varying frequencies and how the destination is maintained to the brain so that the brain will perceive different sounds.

Basilar Membrane

A snail shaped part near the cochlea.

Hearing Capacity

20 hz - 20k hz

Basilar Tuning

This is inside the cochlea and distinguishes the low and high frequencies.

Hair Cells

Located along the basilar membrane, these are receptors in the ears.

Cochlea: Base

Responsible for perceiving high pitch or high frequencies

Cochlea: Apex

Responsible for perceiving low pitch or low frequencies

Cochlea (Unrolled)

Different hair cells are triggered in the _________ depending on the sounds perceived by a human.

• The closer to the base, the higher the frequency.

• The closer to the apex, the lower the frequency.

Primary Auditory Cortex

The destination of signals sent from the ear to the brain to perceive/interpret sound.

Conductive Deafness

The people who suffers with this kind of deafness still has a normal cochlea and auditory nerve, and can hear their own voice.

• Also known as Middle Ear Deafness.

• Sometimes can only be temporary.

• If it persists, can be corrected by surgery or hearing aid.

Nerve Deafness

Caused by a damage in the cochlea, the hair cells, or auditory nerves. If it is confined to one part of the cochlea, it impairs hearing of certain frequencies and not others.

• Also known as Inner Ear Deafness

• Can be inherited.

• Can be acquired from diseases or loud noises.

Tinnitus

A frequent or constant ringing in the ears.

• Maybe due to a phenomenon similar to phantom limb.

  • If the brain no longer gets its normal input, axons representing other parts of the body may invade parts of the brain area that usually responds to sound.

• Other treatments can mask the noise.