FINALS - UNIT 3

Question 1

Outer Ear

Answer 1

Collects sound and funnels it to the tympanic membrane

Changes frequency of sound to aid localization

Question 2

Middle Ear

Answer 2

Sound wave cause eardrum to vibrate

setting bones to in the to motion

Question 3

Inner (Cochlea)

Answer 3

Mechanical vibrations into neural signals

Question 4

Temporal Bone

Components?

Answer 4

• Squamous
• Petrous
• Mastoid
• Tympanic

Question 5

Squamous

Answer 5

thin, fan like

Question 6

Mastoid

Answer 6

contains air cells

Question 7

Styloid Process

Answer 7

No auditory contribution

Question 8

Tympanic Membrane

Answer 8

Pars tensa & Pars Flaccida

Connected to middle ear by Manubrium Malleus

Question 9

Middle Ear components

Answer 9

1. Tympanic Cavity or Tympanum
2. Epitympanic Recess or Attic
3. Mastoid Antrum

Question 10

Tympanic Cavity

Answer 10

Also known as Tympanum

space in the temporal bone behind the TM

Question 11

Epytympanic Recess or Attic

Answer 11

Superior to the level of the TM

Contains portions of the incus and malleus

Question 12

Mastoid Antrum

Answer 12

Enlarged Space in the mastoid part of the temporal lobe

Posterior to epitympanic recess

Question 13

Ossicular Chain is made of

Answer 13

• Malleus
• Incus
• Stapes

Three smallest bones in the body

Question 14

Malleus

Answer 14

Attaches to TM along the manubrium

Head extends into the epitympanic recess

connects to the incus

Question 15

Incus

Answer 15

Transmits vibrations from the malleus to the stapes

Question 16

Stapes

Answer 16

Head attaches to the incus

Anterior crus, posterior crus, and footplate form a stirrup

Footplate attaches to the oval window

Question 17

Sound Transmission through the Middle Ear System

Answer 17

TM → Malleus → Incus → Stapes → Inner Ear

Question 18

Muscles of Middle Ear

Answer 18

Stapedius Muscle

• Smallest in body
• Innervated by 7th Cranial
• Contraction pull stapes posteriorly, stiffening ossicular chain

Tensor Tympani

Innervated by the 5th cranial (trigeminal)

Contraction pulls malleus in the anterior direction and stiffens ossicular chain

Question 19

Acoustic Reflex

Answer 19

Reflexive contraction of stapedius muscles in both ears

stiffens ossicular chain and reduces the transmission of low frequency sounds

Question 20

Acoustic Reflex Functional Importance

Answer 20

• Acts as an automatic volume control
• Protect against long term noise damage
• may improve signal to noise ratios for speech

Question 21

Eustachian Tube

Answer 21

Connects middle ear to pharynx

tilt at 45°

opened by tensor palatini muscle during swallowing and yawning

Question 22

Azmuith

Answer 22

Location of sound source in horizontal plane

Question 23

Elevation

Answer 23

location of sound in the vertical plane

Question 24

Head Shadow Effect

Answer 24

• Head impedes the transmission of high freqs to the far ear
• Because high freq sounds have wavelengths that are smaller, cannot bend around head

Question 25

Pinna Effect

Answer 25

• Affects sounds with Freq > 4000 Hz
• How sound is changed depends on the location of sound source
• Sound Localization

Question 26

Resonant Frequency of Ear Canal

Answer 26

Increases sound levels for frequencies between 2000-5000 with peak gain of 15 dB at 3000-4000 Hz

Question 27

Head Related Transfer Function

Answer 27

Shows changes in sound level due to presence of the head, pinna, and ear canal as a function of frequency

>1500 Hz

Question 28

Binaural Cues

Answer 28

Used for sound localization when two ears present

Question 29

Impendance Matching Mechanisms

Answer 29

1. Area ratio
2. Ossicular Lever
3. Curved membrane

Gain created by these middle ear mechs compensate for 30 dB loss of energy

Question 30

Total gain of the middle ear transformer

Answer 30

Area Ratio 25 dB

Curved Membrane Buckling 6 dB

Ossicular Lever Action 2 dB

total gain 33 dB