Auditory Physiology

Question 1

What sense involves converting sound waves into electrical energy?

Answer 1

Audition (hearing)

Question 2

What type of sound wave is regular with constant amplitude/frequency?

Answer 2

A pure tone

Question 3

What type of sound is a complex wave form that is regularly repeated?

Answer 3

Musical sounds

Question 4

What is sound without a regular pattern called?

Answer 4

Noise

Question 5

What sound intensity level, if frequent, can cause hearing loss?

Answer 5

> 85 dB

Question 6

What are the five main steps of Auditory Processing?

Answer 6

1. External Ear; 2. Middle Ear; 3. Inner Ear; 4. Brainstem/Midbrain; 5. Auditory Cortex

Question 7

What is the primary function of the Pinna?

Answer 7

Sound energy collector

Question 8

What part of the external ear acts as an elevation and frequency-specific sound reflector?

Answer 8

The Concha

Question 9

What are the three bones, or auditory ossicles, in the middle ear?

Answer 9

Malleus, Incus, and Stapes (hammer, anvil, stirrup)

Question 10

What is the main function of the middle ear in sound transmission?

Answer 10

Transmit air-borne sound to fluid-filled cochlea with minimal energy loss

Question 11

How does the middle ear amplify sound pressure?

Answer 11

Due to the area ratio of the tympanic membrane to the oval window (~17:1)

Question 12

What is the Tympanic (acoustic) reflex?

Answer 12

A mechanism that damps loud sounds (protects hair cells)

Question 13

What are the three fluid-filled ducts of the cochlea?

Answer 13

Scala vestibuli, scala media, and scala tympani

Question 14

Which structure in the scala media acts as the transducer of sound and frequency analyzer?

Answer 14

The basilar membrane

Question 15

How does the basilar membrane’s stiffness vary from base to apex?

Answer 15

Narrow and stiffer at the base (high frequency) Wider and more flexible at the apex (low frequency)

Question 16

What is the tonotopic map?

Answer 16

Mapping of sound frequency (high → low) along the basilar membrane

Question 17

What fluid is in the scala media and what is its K+ and potential like?

Answer 17

Endolymph: high K+ with a +80 mV potential (endocochlear potential)

Question 18

What is the potential difference between endolymph and perilymph called?

Answer 18

Endocochlear potential (EV)

Question 19

What causes the bending of cilia in the organ of Corti?

Answer 19

Vibration of the organ of Corti against the tectorial membrane

Question 20

What happens when the cilia bend towards the taller stereocilia?

Answer 20

Mechanically sensitive K+ channels open , leading to K+ influx and depolarization

Question 21

What does hair cell depolarization induce?

Answer 21

Voltage-gated Ca2+ channel opening , causing neurotransmitter release

Question 22

What is the main function of the inner hair cells (IHC)?

Answer 22

Convert sound vibration to electrical impulses

Question 23

What is the motor protein responsible for the movement of outer hair cells?

Answer 23

Prestin

Question 24

How do the outer hair cells (OHC) enhance hearing?

Answer 24

Their motility (motor function) enhances basilar membrane motion, sharpening frequency selectivity and creating a cochlear amplifier

Question 25

Where do Spiral Ganglion Cell (SGC) afferents first carry the tonotopic map?

Answer 25

To the cochlear nucleus (CN)

Question 26

What auditory structures maintain the tonotopic organization?

Answer 26

The organization runs from the basilar membrane through the CN to higher auditory CNS

Question 27

Which auditory structure is the first point of integration for information from both ears?

Answer 27

The Superior Olivary Complex (SOC)

Question 28

What cue is dominant for low frequency sound localization?

Answer 28

Interaural Time Differences (ITD)

Question 29

What cue is dominant for high frequency sound localization?

Answer 29

Interaural Level/Loudness Differences (ILD)

Question 30

Which part of the SOC is sensitive to ITDs and acts as a coincidence detector?

Answer 30

Medial Superior Olive (MSO)

Question 31

Which part of the SOC is sensitive to ILDs?

Answer 31

Lateral Superior Olive (LSO)

Question 32

What type of hearing loss results from damage to the external or middle ear?

Answer 32

Conductive Hearing Loss (HL)

Question 33

What type of hearing loss results from irreversible damage to the cochlea's sensorineural tissues or CNS?

Answer 33

Sensorineural Hearing Loss (SNHL)

Question 34

What are two examples of ototoxic drugs that cause SNHL?

Answer 34

Kanamycin (antibiotic) and Furosemide (diuretic)

Question 35

What is Presbycusis?

Answer 35

Age-associated sensorineural hearing loss (SNHL)

Question 36

In Presbycusis, which frequencies are first affected?

Answer 36

High frequency

Question 37

What is the result of the Rinne test for a person with Sensorineural HL?

Answer 37

Air > bone (sound louder through air)

Question 38

What is the result of the Rinne test for a person with Conductive HL?

Answer 38

Bone > air (sound louder through bone)

Question 39

How does the Weber test localize sound in a person with Sensorineural HL?

Answer 39

Sound lateralizes to the Normal ear

Question 40

How does the Weber test localize sound in a person with Conductive HL?

Answer 40

Sound lateralizes to the Affected ear