Section 1.2 Middle Ear

Question 1

What is Natural Frequency?

Answer 1

The frequency at which a system will oscillate if disturbed by an external force.

Question 2

Explain the relationship between a input, system, output and gain. (draw it)

Answer 2

input is processed by a system, resulting in a difference between input and output

Gain = change (difference) of signal amplitude and varies with frequency response

Question 3

What is Frequency Response?

Answer 3

Measures of how gain is changed with frequency, gain as the function of frequency (the effect of an object on the frequency balance of signals passing through it)

Question 4

Natural Frequency is determined by m________ and s______.

Answer 4

mass and stiffness

Question 5

What is friction?

Answer 5

Force resisting the relative motion of an object

Question 6

The input frequency __________ to the natural frequency will have the __________ output– frequency selectivity!

Answer 6

Closer
Higher

Question 7

What are the three components of impedance?

Answer 7

mass, stiffness and fiction (resistance) only the mass and stiffness are related to frequency.

Question 8

What can we see from this equation?
Xm= 2.pi.f.m

Answer 8

We can see that the mass component increases
with frequency Mass itself (m) is fixed in each system. So larger frequency, larger mass component.

Question 9

We can see that the stiffness component ____________ if frequency
were to __________.So,
larger frequency means smaller stiffness.

Answer 9

Xc = s/2.pi.f

Question 10

Acoustic impedance is how much _________ energy is ___ ___________

Answer 10

It’s how much sound energy is NOT ABSORBED

Question 11

Carpets absorb sound and it isn’t bouncing
off the walls (reverberating) like in a gym. So it has___________ impedance

Answer 11

Low impedance

Question 12

Sound waves through air bounce back at 99.9% off water. So water has _________ impedance

Answer 12

High impedance

Question 13

Consider the middle ear. Sound is absorbed when it goes from the ear canal and the ossicular
chain is set in motion: __________impedance means that a lot of that sound is ___________.

Answer 13

low
absorbed

Question 14

What is the resonant frequency of the ear canal?

Answer 14

3200Hz

Question 15

What is the length of the ear canal?

Answer 15

2.6cm

Question 16

What is the width of the ear canal?

Answer 16

0.7 cm in diameter

Question 17

What is reactance?

Answer 17

The
contributions of mass and stiffness to impedance

Question 18

The object will vibrate differently in response to different frequencies of different signals, this is called:

Answer 18

frequency selectivity

Question 19

True or false: Even if the signal is not at natural frequency of a system, it can still vibrate.

Answer 19

True, just not at max amplitude

Question 20

Which is the biggest contributor of the EE in terms of dB amplitude and how much?

Answer 20

Meatus (canal)
15 dB

Question 21

In hearing, we want GOOD ____________ and GOOD __________ resolution. It is hard to do, but it is achieved by the ________

Answer 21

frequency selectivity temporal resolution
Cochlea

Question 22

A system that has better frequency selectivity has poorer________.

Answer 22

temporal resolution

Question 23

___ friction, light damping, vibration will last _______. (poorer temporal resolution)

Answer 23

Low longer

Question 24

___ friction, large damping, vibration will stop _________. (Better temporal resolution)

Answer 24

high
quickly

Question 25

What causes an object to vibrate? What varies about each object?

Answer 25

Vibrate in response to a driving force with various frequencies, their natural frequencies vary though.

Question 26

What is frequency selectivity? (related to input/output)

Answer 26

The input frequency closer to the nat. frequency will have higher output (frequency selectivity)

Question 27

d) When pushing a swing, what will not affect the frequency and what are the factors that will?

Answer 27

The way you push the swing will not affect the frequency of the swing, only the length of the rope and the mass of the girl

Question 28

How do each of components of impedance relate to frequency?

Answer 28

Mass increases with frequency Stiffness decreases with frequency Resistance does not change with frequency

Question 29

According the the reactance graph, which components are in opposing phases? (180 degrees)

Answer 29

Mass and stiffness

Question 30

Describe frequency selectivity in one sentence.

Answer 30

The object will vibrate differently in response to different frequencies of signal but more to its natural frequency

Question 31

What is damping?

Answer 31

Light damping, less absorption thus more vibrations Large damping, more absorption thus more vibrations

Question 32

What is the friction effect as it relates to damping?

Answer 32

Low friction, light damping, vibration will last long time (not stop quickly), this is poorer temporal resolution High friction, large damping, vibration stop quickly, better temporal resolution

Question 33

d) What is the friction effect as it relates to BOTH damping and frequency selectivity?

Answer 33

Low friction—smaller damping, narrow frequency response (better frequency selectivity) High friction—larger damping, broader frequency response (poorer frequency selectivity

Question 34

a) What is the general ratio measured by gain?

Answer 34

Output/input

Question 35

Explain how the external ear acts like a tube in relation to resonant frequency (one sentence, brief)?

Answer 35

When air particles are vibrated by sound of various frequencies, the greatest amplitude is seen at the resonant/natural frequency.

Question 36

How would the frequency response be measured for the canal? For the concha?

Answer 36

, we compare two measurements: one is for input and the other is for output. For example, M1 is the measurement of input to Flange, M2 is the output of Flange, or the input to Concha. At any frequency, input/output gives gain. Frequency-gain relationship is frequency response.

Question 37

The external ear resonance is based on the average of gain of which three parts?

Answer 37

Meatus, Concha and flange

Question 38

Which of the three parts responsible for EE resonance the largest contributor to the overall gain?

Answer 38

Meatus

Question 39

What is the overall gain at the average ear canal resonance?

Answer 39

15 dB

Question 40

Which of the three parts responsible for EE resonance has a peak at lower frequency relative to the others?

Answer 40

Meatus has a peak at lower frequency

Question 41

Which of the three parts responsible for EE resonance has a peak at higher frequency relative to the others?

Answer 41

Concha has a higher frequency peak

Question 42

e) What is the approximate resonance frequency of the whole external ear?

Answer 42

3200Hz

Question 43

f) How does resonant frequency change with age?

Answer 43

Higher resonant frequency at a younger age and 37 months closer to adult frequency, because of lengths of the canal

Question 44

What is the second function of the external ear canal?

Answer 44

Provide cues for localization

Question 45

What are two categories of EE localization cues cues?

Answer 45

Spectrum cues due to the transfer of function of the EE Differences in signals received by the two ears (binaural cues)

Question 46

What term is transfer function f similar to?

Answer 46

Frequency Response

Question 47

What is another name for the pinna effect?

Answer 47

Pinna cues

Question 48

a) What are the three ways the external ear protects the eardrum?

Answer 48

Irregular shape (S configuration) ceruminous (wax) Hairs

Question 49

\What are three ‘protective’ components inside the ear canal? What fraction of the ear canal has these (laterally/medially)?

Answer 49

Outer 1/3 of the canal has hairs, sebaceous (oil) and ceruminous (wax) glands

Question 50

c) How many degrees is the tympanic membrane angled with reference to the axis of the canal? What purpose does this serve?

Answer 50

45 degrees with the axis of the canal, reducing the impact of hitting by a foreign body

Question 51

What is the self-cleaning mechanism of the ear canal

Answer 51

The slow growth of cells and the migration of them push debris out of the ear canal. Epidermal migration produces “wrinkles

Question 52

What is another name for the eardrum?

Answer 52

Tympanic Membrane

Question 53

What is the (general) definition of a ligament?

Answer 53

Ligaments are elastic tissue which connect bones to other bones.

Question 54

How many ligaments are/is there connected to the malleus? What are/is they/it?

Answer 54

3: Superior, lateral, anterior.

Question 55

How many ligaments are/is there connected to the incus? What are/is they/it?

Answer 55

1: Posterior

Question 56

How many ligaments are/is there connected to the stapes? What are/is they/it?

Answer 56

1: Annular ligament

Question 57

What does the manubrium attach to?

Answer 57

The TM—umbo

Question 58

Describe the rotation of the eardrum in relation to the bone chain.

Answer 58

- Lever like motion between malleus and incus connection - Malleus and incus are rotated around its pivot, causing the eardrum to vibrate unevenly - The largest vibration is on the inferior part of the eardrum

Question 59

What are the four main parts included in the malleus

Answer 59

Head, neck, lateral process, manubrium

Question 60

What are the 4 main parts in the incus?

Answer 60

Body, short process, long process, lenticular process

Question 61

What are the four main parts of the stapes?

Answer 61

Head, neck, anterior/posterior crus, footplate.

Question 62

What is one technique to tell which ear it is based on the tympanic membrane?

Answer 62

Either looking at the cone of light or the long process of the incus

Question 63

What is the more known nerve that the chorda tympani is part of? What is its main role?

Answer 63

Facial nerve. The role of the chorda tympani is to carry taste from the ipsilateral half (same side) of the tongue.

Question 64

What does ‘manubrium’ mean?

Answer 64

Handle Lateral part of the Malleus

Question 65

How many layers do the pars flaccida and pars tensa have?

Answer 65

Pars flaccida: two layers (no fibrous layer). Pars tensa: Three layers

Question 66

Flaccida vs. Tensa What purpose does one not having the fibrous layer serve?

Answer 66

The pars flaccida is more flexible and serves as an air pressure buffer. Note: It does not attach to the bone chain and is therefore NOT responsible for sound conduction.

Question 67

Flaccida vs. Tensa Describe the tenseness of one relative to the other?

Answer 67

The pars tensa is stiffer.

Question 68

Flaccida vs. Tensa which one is thicker?

Answer 68

The pars flaccida.

Question 69

Flaccida vs Tensa Which one is dorsal to the other? What is at the border between the pars tensa and pars flaccida (which nerve and which ligament)?

Answer 69

Pars flaccida is dorsal. Annular ligament and chorda tympani (a branch of the facial nerve) are at the border between the pars tens and pars flaccida.

Question 70

Which view (medial or lateral) can we see the two parts of the eardrum?

Answer 70

Lateral

Question 71

What is the self-cleaning mechanism of the ear canal?

Answer 71

Epidermal migration—the slow growth of cells and the migration of them push debris out of the ear canal.

Question 72

What shape is the ear drum and which side does it tilt to?

Answer 72

concave and tilts 45 degrees from its top laterally

Question 73

Which part of the malleus separates the pars flaccida from the pars tensa?

Answer 73

Lateral Process

Question 74

How many layers is the ear drum made of?

Answer 74

4 layers

Question 75

How long is the ET?

Answer 75

3.5 cm

Question 76

Which ossicular bone is the largest?

Answer 76

The malleus

Question 77

What is the formula of impedance?

Answer 77

Question 78

What is part of the posterior (mastoid) wall of the tympanic cavity? (4)

Answer 78

Aditus antrum stapedius muscle (pyramidal eminence) Incudal fossa: indention in bone for the incus Chorda tympani nerve entrance: branch of CN7

Question 79

What is part of the Medial (labyrinthine) wall (5)?

Answer 79

Round window Oval window (covered by stapes footplate) Facial nerve canal Prominence of lateral semicircular canal Cochlear promontory

Question 80

What is part of the Superior (tegmental) wall? (1)

Answer 80

Epitympanic recess or attic provides space for heads of malleus and incus

Question 81

What is part of the Inferior (tympanic) wall?

Answer 81

Separates ME from jugular bulb below

Question 82

What is part of the Lateral (membranous) wall?

Answer 82

Tympanic membrane

Question 83

What is part of the Anterior Wall? (3)

Answer 83

Tensor tympani tendon/muscle entrance Eustachian tube orifice (opening) Internal carotid canal