Physiology Of Hearing

Question 1

Sound is a pressure caused by ______________, set in motion by a ____________

Answer 1

Sound is a pressure caused by oscillating molecules, set in motion by a vibration

Question 2

_______ dictates pitch, ________ dictates intensity

Answer 2

Frequency dictates pitch, amplitude dictates intensity

Question 3

Process of hearing

1) ________ ear collects sound and directs ________ waves into the ____________

Answer 3

1) External ear collects sound and directs sound waves into the tympanic membrane

Question 4

Process of hearing

2) The ________ arrive at the tympanic membrane, triggering _______ there as well

Answer 4

2) The vibrations arrive at the tympanic membrane, triggering vibrations there as well

Question 5

Process of hearing

3) This vibation stimulates the ______________________________, which transmits the energy to the _________

Answer 5

3) This vibation stimulates the ossicular chain of the middle ear, which transmits the energy to the cochlea

Question 6

Process of hearing

4) The middle ear acts as _________________

Answer 6

4) The middle ear acts as an amplifier mechanism

Question 7

How does the middle ear act as an amplifier

Answer 7

The ossicles decrease in size in the inner ear which concentrates the sound energy.

The oval window is much smaller than the tympanic membrane which increases pressure.

This increased pressure & increased concentration of energy helps transmit the sound into the inner ear.

Question 8

What is the importance of the middle ear as an amplifier

Answer 8

It bridges the gap between the air pressure in the outer ear and the fluid filled inner ear, which would otherwise dampen sound waves.

Without amplification by the middle ear bones (ossicles), only a very small amount of sound energy would reach the inner ear to be processed as sound

Question 9

Process of hearing

5) The inner ear receives the ____________ signals from the middle ear and converts them into ____________ signals

Answer 9

5) The inner ear receives the mechanical signals from the middle ear and converts them into electrical signals

Question 10

Process of hearing - how is mechanicl energy converted to electrical energy?

5a) Footplate of stapes vibrates in oval window which creates _________ waves in the ____________

Answer 10

5a) Footplate of stapes vibrates in oval window which creates pressure waves in the perilymph of the cochlea

Question 11

Process of hearing - how is mechanicl energy converted to electrical energy?

5b) The wave motion is transmitted to the ________ inside the cochlear duct

Answer 11

5b) The wave motion is transmitted to the endolymph inside the cochlear duct (scala media)

Question 12

Process of hearing - how is mechanicl energy converted to electrical energy?

5c) As a result the ______ membrane vibrates, which causes the ______ cells of the organ of _____ to move

Answer 12

5c) As a result the basilar membrane vibrates, which causes the hair cells of the organ of Corti to move

Question 13

Process of hearing - how is mechanicl energy converted to electrical energy?

5d) The hair cells move against the ________ membrane which stimulates the cells to __________

Answer 13

The hair cells move against the tectorial membrane which stimulate the cells to depolarise

Question 14

Process of hearing - how is mechanicl energy converted to electrical energy?

5e) The depolarisation results in the stimulation of _______ and then the central pathways

Answer 14

CN VIII

Question 15

What is the functional unit of the cochlear & where are the cells located

Answer 15

Inner hair cells in the Organ of Corti

Question 16

What is the role of hair cells

Answer 16

responsible for converting sound vibrations into electrical signals by the release of neurotransmitters

Question 17

Process of hearing

6) the electrical signal travels along CN VIII and culminates in the __________________ of the ______________________

Answer 17

the electrical signal travels along CN VIII and culminates in the primary auditory cortex of the left superior temporal gyrus

Question 18

Process of hearing

7) The pressure waves in the cochlear duct and become vibrations again, and are dampened at the _____________

Answer 18

Round window

Question 19

Where is the primary auditory cortex located in the brain

Answer 19

Left posterior superior temporal gyrus

Question 20

At what week gestation does the foetus begin to hear

Answer 20

18 weeks

Question 21

At what week gestation does the foetus begin to respond to sound/voice

Answer 21

26 weeks

Question 22

What is the role of the Eustachian tube

Answer 22

It is a ventilation pathway for middle ear mucosa

Question 23

Is the Eustachian tube closed or open at rest

Answer 23

Closed

Question 24

The Eustachian tube may open to ‘equalise pressure of the ear’. What two muscles are involved in this

Answer 24

tensor veli palatini & levator palatine muscles