Exam 1 Flashcards
1
Q
What is a transducer?
A
Changes one form of energy into another form of energy.
Ex: Ear changes acoustic energy into mechanical energy.
2
Q
Ear Resonance and main functions
Outer:
Middle:
Inner:
A
Outer: catches and funnels sound waves
Middle: changes sound waves to mechanical energy
Inner: changes mechanical energy to electrical energy for transmission to the brain
3
Q
2 Parts of the Outer Ear
1.
2.
A
- Pinna: portion of ear you see, cartilaginous
2. External Auditory Canal (EAC)
4
Q
Main functions of Outer Ear:
1.
2.
A
- Sound transmission
2. Ear Protection
5
Q
Which part of the ear is the outer ear?
A
Portion external to tympanic membrane
6
Q
Sound waves are influenced by their 3 components:
1.
2.
3.
A
- Energy source (lungs)
- Vibrating object (vocal folds in speech)
- Elastic medium (Air)
7
Q
3 acoustic effects when sound waves encounter a barrier in space:
1.
2.
3.
A
- Diffraction
- Reflection
- Absorption
8
Q
Why is the pinna shaped the way it is?
A
To funnel sound into the ear canal
9
Q
Function of Pinna:
A
To gather sound and aid in localization
10
Q
Structure of Pinna:
Shape:
Length:
A
Shaped: “s” shaped
Length: 25 mm effective acoustic length plus end effect of concha = 30mm
11
Q
Structure of Pinna:
Lateral 1/3:
Medial 2/3:
A
Lateral 1/3 - Cartilaginous
Medial 2/3 - Bony
12
Q
Function of EAC:
1.
2.
A
- Sound transmission (with pinna- amplifies sound)
2. Ear Protection (twisty canal protects tm) (ceruminous and sebaceous glands in cartilaginous portion)
13
Q
Cupping the ear can increase intensity by:
A
8 dB
14
Q
The EAC is which type of air column:
A
Closed at one end
15
Q
Concha
A
the bowl of the ear, increases the length of EAC by 5mm
16
Q
Localization:
A
Finding the direction of where a sound is coming from
17
Q
Planes of Localization:
A
- Azimuth Estimation: Horizontal Plane (0 degrees in front of nose)
- Elevation Estimation: Vertical Plane
18
Q
Spacial Orientation:
A
Finding the localization of a sound source PLUS the distance from the sound source
19
Q
Planes of Spacial Orientation:
A
- Azimuth Estimation: Horizontal Plane (0 degrees in front of nose)
- Elevation Estimation: Vertical Plane
- Distance Estimation: Distance from sound source
20
Q
Monaural Localization
A
One ear
Localization in vertical plane
Localization of front vs back of head
21
Q
Binaural Localization
A
Two ears ( AND difference between the two) Localization in horizontal plane
22
Q
Binaural Localization Cues:
1.
2.
A
- IID - Interaural Instensity Difference
2. ITD Interaural Time Difference
23
Q
Binaural Localization: IID
1. Frequencies:
A
- High frequencies- they bend around head well whereas low frequency sounds don’t
24
Q
Binaural Localization: ITD
- Frequencies:
- Directly related to:
A
- Low frequencies
2. Directly related to phase (which phase is the soundwave in when it hits the ear)
25
HRTF: Head related transfer functions
How the sound waveform changes because the person is present in the space
26
What is Impedence?
Opposition to the flow of energy
27
The middle ear is filled with________.
Air
28
Which structures compose the middle ear?
1. Tympanic Membrane
2. Air-Filled Cavity
3. Ossicles
4. Eustachian Tube
5. Muscles and Nerves
29
Tympanic Membrane Layers
1.
2.
3.
1. Lateral Epithelial
2. Middle Fibrous
3. Medial Mucosa
30
Shape of Tympanic Membrance:
Conical
31
Superior vs Inferior Tympanic Membrance
Superior: Pars flaccida - more flaccid
Inferior: Pars tensa - more tense
32
Tympanic Cavity Layers
1.
2.
3.
1. Epitympanium
2. Mesotympanium
3. Hypotympanium
33
Ossicles:
1.
2.
3.
1. Malleus
2. Incus
3. Stapes
34
The Eustachian Tube Connects:
The Nasopharynx and the Tympanic Cavity
35
Eustachian Tube: Childrens Adult
Child: shorter and more horizontal
Adult: longer, more vertical
36
Eustachian Tube Dysfunction
Short-term effects:
Long-term effects:
Short-term: pain, temp hearing loss, distortion of sound, increase risk of infection
Long-term: fluid build-up, choleseatoma ( neg pressure pulls ear drum in and pieces of skin break off and build up)
37
Middle Ear Muscles: Stapedius Muscle
Location:
Function:
Location: posterior wall of tympanic cavity
Function: acoustic reflex ( when exposed to loud sound, contracts, tightening ossicular chain and protecting hair cells of inner ear) Happens above 80 dB.
38
Middle Ear Muscles: Tensor Tympani Muscle
Location:
Function:
Location: anterior wall of tympanic cavity
Function: Unsure- we don't know much about it
39
Functions of Middle Ear:
1.
2.
3.
1. Sound transmission "Impedance Transformer"
2. Pressure Equalization
3. Inner Ear Protection
40
How does the middle ear act as an impedance transformer?
1.
2.
3.
1. Pressure transformer
2. Ossicular lever
3. Catenary lever
41
Problem of getting sound from air to cochlea?
Sound goes from one medium (air) to another (fluid in the cochlea).
Fluid = higher impedence
Higher impedence = decrease in pressure (intensity)
Thus, middle ear acts as impedence transformer.
42
What are the two main ways of matching impedance between air in the ear canal and fluid in the cochlea?
1.
2.
1. Pressure transformer
| 2. Ossicular Lever
43
Pressure Equalization:
Eustachian tube allows for adjustment of pressure. If Eustachian tube is blocked, pressure cannot be adjusted.
44
Pressure in tympanic cavity should equal _________.
atmospheric pressure
45
Eustachian Tube
Closed:
Open:
Closed: normally closed
Open: opens as needed to equalize pressure ex when yawning, swallowing
46
Eustachian Tube
Closed:
Open:
Closed: normally closed
Open: opens as needed to equalize pressure ex when yawning, swallowing
47
Valsalva Maneuver
opens Eustachian tube
| increases pressure in tympanic cavity
48
Toynbee maneuver
opens Eustachian tube
| decreases pressure in tympanic cavity
49
Both muscles of the middle ear, Tensor Tympani and Stapedius, work to _____________.
Why?
Stiffen the middle ear system.
Increase in stiffness = increase in impedance
Increase in impedance = sound does not flow as efficiently
50
If the acoustic reflex of the stapedius muscle does occur, why can noise still damage hearing?
1.
2.
3.
1. Latency of the response (it takes time for the reflex to be triggered)
2. Frequencies affected (protects most against low frequency sound)
3. Amount of protection/attenuation (reflex may provide up to 15 dB of attenuation of loud signal, not necessarily enough to protect from all loud sounds)
51
If the acoustic reflex of the stapedius muscle does occur, why can noise still damage hearing?
1.
2.
3.
1. Latency of the response (it takes time for the reflex to be triggered)
2. Frequencies affected (protects most against low frequency sound)
3. Amount of protection/attenuation (reflex may provide up to 15 dB of attenuation of loud signal, not necessarily enough to protect from all loud sounds)
52
Tonotopic Organization
Tono = ___________
Topic = ___________
Tonotopic = _______
```
Tono = sound
Topic = location
Tonotopic = location of a sound
```
Organ of Corti is organized tonotopically by frequency
53
Tonotopic Organization:
Low frequency sounds:
High frequency sounds:
Low frequency sounds processed at the apex of the basilar membrane (cochlea)
High frequency sound processed at the base of the basilar membrane (cochlea)
54
The base of the cochlea has a _____ resonance frequency, and as you move toward the apex of the cochlea, the resonant frequency progressively _______.
higher; lowers
55
Resonance frequency:
Natural frequency at which it is easiest to get an object to vibrate
56
Resonance frequency:
Natural frequency at which it is easiest to get an object to vibrate
57
Basilar Membrane:
Membrane that travels the length of the cochlea with variances in mass and stiffness along it's length
58
Basilar Membrane
Base:
Apex:
Base: Thin, (low mass), stiff-----> higher resonance frequencies
Apex: Thick (large mass), flaccid----> lower resonance frequencies
59
Basilar Membrane Motion:
Travelling wave - transverse wave (displaces particles perpendicular to wave)
60
Basilar Membrane transverse waves travel through:
Scale vestibule, scala media, and scala tympani
61
The inner ear structures for hearing:
1.
2.
1. Cochlea
| 2. Auditory Nerve - Cranial Nerve 13 - Vestibulocochlear nerve
62
Cochlea:
Location:
# of Turns:
Length:
Temporal Bone in skull
2 3/4 turns
~35mm in length
** NOT free standing-- it's a space of this shape within the temporal bone**
63
3 layers of the 'bony labyrinth' of the cochlea:
1.
2.
3.
1. Bony Labyrinth - outside mold- part of temporal bone
2. Membraneous Labrynth - follows the twists of bony labyrinth- filled with endolymph
3. Perilymph - fluid between the bony labyrinth and membranes
64
3 fluid-filled channels in cochlea: (FORMED BY 2 membranes)
1.
2.
3.
1. Scala Tympani -filled w/perilymph
2. Scala Vestibuli - filled w/ perilymph
3. Scala Media - filled w/endolymph
65
Helicotrema:
Point in cochlea where scala vestibule and scala tympani connect
At the apex (innermost) of the cochlea
66
Which two membranes divide the cochlea into 3 channels or tunnels:
1.
2.
1. Reissner's Membrane
| 2. Basilar Membrane
67
Syria vascularis
Tissue that covers the spiral ligament within the scala media
Rich in blood supply
68
Reisners membrane
Separates Scala vestibuli from scala media
Connects to spiral limbus at center
Connects to Syria vascularia at edge
69
Basilar Membrane
Separates scala media from scala tympani
Connects to spiral lamina at center
Connects to spiral ligament at edge
70
Organ of Corti
Function
Location
Sensory structures for hearing, transducers mechanical energy into chemical/electrical
In the scala media, sits on basilar membrane
71
Scala Media
Aka
Superior border
Inferior border
Aka cochlear duct
Superior border reisners membrane
Inferior border basilars membrane
72
```
Main structures of Organ of Corti
1.
2.
3
4
```
1. Support cells and tunnel of corti
2. Hair cells (inner and outer)
3. Reticular lamina- upper surface of organ of corti
4. Tectorial membrane: covers all of organ of corgi-tallest stereocillia embed here
73
Hair cells:
Outer:
Inner:
Sensory organs with stereocillia at one end
Outer: 3 rows, cylindrical, 12000
Inner: 1 row, flask shaped, 3500
74
Stereocillia
Arranged:
Form:
Tallest to shortest on top of hair cell
Form the upper surface of the organ of corti (reticular lamina)
Stereocillia projects through reticular lamina and are in endolymph
75
Levers:
Ossicular:
Catenary:
Ossicular: length of malleus>length of incus relative length of middle ear bones create a lever that increases pressure to ow
Catenary:
76
Shearing motion of stereocillia:
Because they are stick in between two membranes that move in opposite directions they bend =shearing motion
77
Outer hair cells are ______ while inner hair cells are not.
Mobile
78
Place theory
Auditory nerve is organized tonotopically, hair cells at basilar membrane cause firing of nerves turned to high frequencies, at apex of basilar membrane cause firing at low frequencies.
79
Periodicity Theory:
| Problem:
The rate at which nerves fire is what codes frequency
| Problem: single nerve can only fire 1000x/sec, how do we account for greater than 1000hz
80
Volley theory
Problem:
Most accepted theory in field
Multiple neurons working together can code frequencies higher than 1000 hz
Problem: even with volley theory we can only code up to 5000hz: likely that aspects of place and periodicity theory account for coding of signals to the brain
81
Intensity coding
Greater intensity sounds produce a broader traveling wave in the cochlea
82
Firing rate of nerves:
Nerves fire spontaneously without stimulation, but stimulation increases firing rate.
