Physiology - Hearing

Question 1

How is sound produced

Answer 1

Produced by vibrating objects that causes compression and rarefication of air molecules.

Question 2

What is a sound wave

Answer 2

The distance between two compression sites.

Question 3

What does the peak of a sound wave show

Answer 3

Shows the most compressed air molecule site.

Question 4

What does the bottom of a sound wave show

Answer 4

Shows the most rarified air molecule site.

Question 5

What is frequency

Answer 5

The pitch of sound

Question 6

What does low frequency show

Answer 6

Low pitch sound

Question 7

What does high frequency show

Answer 7

High pitch sound

Question 8

What frequency can humans detect

Answer 8

16-20 000 Hz

Question 9

What is amplitude

Answer 9

Describes the pressure difference between the maximum and minimum point.

Question 10

What does amplitude show

Answer 10

The loudness of the sound.

Question 11

What does low amplitude show

Answer 11

Soft sounds.

Question 12

What does high amplitude show

Answer 12

Loud sounds.

Question 13

What amplitude can the human ear hear

Answer 13

0-120 dB

Question 14

What is the threshold of hearing

Answer 14

0 dB

Question 15

What is the “quite sound” range

Answer 15

30-60 dB (library or office)

Question 16

What is the “moderate intensity sounds” range

Answer 16

60-90 dB (traffic)

Question 17

What is the “very loud sounds” range

Answer 17

90-110 dB (airplane or train)

Question 18

What is the “uncomfortable range”

Answer 18

> 110 dB (firearm or ambulance)

Question 19

What is the “damage to hair cells in organ of Corti” range

Answer 19

> 85 dB

Question 20

What happens if hair cells in the organ of Corti are damaged

Answer 20

They do not regenerate, if they are lost some parts of hearing is lost too.

Question 21

What is the difference in pressure exerted from 0 to 120 dB

Answer 21

1,000,000 times difference

Question 22

What are the components of the hearing sensory system

Answer 22

1. Receptors = hair cells
2. Conductive part = hearing pathway
3. Highest centers = superior temporal gyrus

Question 23

Explain “receptors” of the hearing sensory system

Answer 23

1. They are located in the inner ear in the organ or Corti.
2. The hair cells generate a receptor potential which released neurotransmitters on the cochlear nerve endings.

Question 24

Explain “conductive part” of the hearing sensory system

Answer 24

1. If the threshold is reached, the action potentials are sent (by cochlear nerves) to the cochlear nuclei (in the brainstem).
2. From the cochlear nuclei, impulse travels to the superior olivary nuclei of both sides.
3. From the superior olivary nuclei they go to the inferior colliculi.
4. Then they go to the medial geniculate bodies.

Question 25

Explain "highest centers" of the hearing sensory system

Answer 25

From the medial geniculate bodies the impulses travel to the superior temporal gyrus in the cerebral cortex where the primary auditory area is.

Question 26

In what ways can sound waves int he organ of Corti be conducted

Answer 26

Through air and bone conduction.

Question 27

Explain air conduction in the organ of Corti

Answer 27

1. Sound wave is conducted to the external auditory canal. 2. They then go into the tympanic membrane of the middle ear. 3. Ossicle chain in the middle ear send the sound waves to the oval window and come in contact with the fluid in the inner ear. 4. The sound waves travel through the fluid into the Corti organ hair cells. 5. Sound is perceived through air.

Question 28

Explain bone conduction in the organ of Corti

Answer 28

1. The vibrations come in contact with the skin and vibrates the skull bones. 2. Sound waves are conducted into the fluid of the inner ear by the temporal bone. 3. The sound waves travel through the fluid into Corti organ hair cells. *Bone conduction is usually weaker than air conduction*

Question 29

Functions of the external ear

Answer 29

- Collection of sound waves. - Transmission of sound waves. - Resonance function. - Defense function. - Regulates humidity and temperature of the tympanic membrane.

Question 30

External ear: explain "collection of sound waves"

Answer 30

Auricula collects sound waves from the external environment.

Question 31

External ear: explain "transmission of sound waves"

Answer 31

Sound waves are transmitted from auricle through the external auditory canal into the tympanic membrane.

Question 32

External ear: explain "resonance function"

Answer 32

This is when the sound waves are amplified ain the external auditory canal. Auricula - resonates to 5000 Hz External auditory canal - resonates to 3000 Hz

Question 33

External ear: explain "defence function"

Answer 33

Glands in the wall of the outer part of the external auditory canal and consists of desquamated epithelial cells that are ear wax. Glands secretions are a little acidic: - Prevents bacterial growth - Inhibits water and insects from entering If ear wax is over excreted: - Results in obstruction - Some function of ear wax is gone - Sound waves cannot penetrate as easily.

Question 34

External ear: explain "regulates humidity and temperature of the tympanic membrane"

Answer 34

Blood flow to the external auditory canal and tympanic membrane maintains temperature and humidity. This allos vibration from sound waves to enter the membrane.

Question 35

What happens in the ossicle chain

Answer 35

When sound has entered the tympanic membrane, it starts to cause vibration in the ossicle chain. Ossicle chain consists of bones: malleus, incus and stapes. The vibration causes the stapes to be pushed into the oval window so that the vibration can be transmitted into the fluid in the inner ear.

Question 36

What are the functions of the middle ear

Answer 36

- Sound transmission. - Amplification. - Defence function. - Equilibrium of pressure.

Question 37

Middle ear: explain "sound transmission"

Answer 37

Ossicle chain transmits sound from the tympanic membrane to the oval window.

Question 38

Middle ear: explain "amplification"

Answer 38

Surface area: surface area of tympanic membrane is 17x more than of oval window = sound is amplified 17 times. Lever system: - Incoming lever of malleus - Outgoing lever of incus If tympanic membrane moves it moves the lever causing 1.3x more pressure on the oval window. - 17 * 1.3 = 22x (amplification). If the ossicle chain becomes immobile, 1.3x amplification is lost. Person will hear whispering, 20-40 dB is lost. A artificial stapes can be inserted in this case.

Question 39

Middle ear: explain "defence function"