Hearing and Balance Flashcards
Pinna
Visible part of the outer ear
Ear canal
Part of the outer ear Channels sound waves to the ear drum.
What separates the outer ear from the middle ear?
The ear drum or Tympanic Membrane.
Tympanic Membrane
Sound waves make the tympanic membrane vibrate.
What are Ossicles and what do they do? Name the Ossicles.
They are 3 bones that pick up vibrations from the ear drum (tympanic membrane) and pass them to the inner ear. 1. Malleus (Hammer) 2. Incus (Anvil) 3. Stapes (Stirrup)
The inner is is filled with air/fluid?
Fluid
Cochlea
It is a snail like shell filled with fluid. Vibrations in the cochlea are received through either:
- Outer/middle ear
- Skull by skull conduction
Auditory Nerve
Information from the cochlea is detected by the auditory nerve, leading directly to the cortex of the brain.
Eustachian Tube
Is connected to the passage of the nose and throat.
It equalizes pressure between the outer atmosphere and the inner ear.
What is the vestibular system made up of?
- Semi-circular canals
- Otoliths
What do the semi-circular canals measure and how many are there?
The 3 semi-circular canals measure angular acceleration (yaw, roll, pitch)
Name the Otoliths.
What do they do?
- Utricle
- Saccule
They consist of hair cells, which sense linear acceleration (anything over 0.1m/s2)
The Vestibular system sends information to ______ and it perceives ______.
The Cerebellum, which perceives balance.
The Audible Range is:
20-20.000Hz
What is the most sensitive audible range?
750 - 4.000 Hz
Which tones are the most distracting?
High frequency tones
Which is more disruptive:
Intermittent noise and sudden noise
or
Continuous noise?
Intermittent and sudden noise
Desibals (dB) is measured on a _______ scale.
logarithmic scale (low change in dB is a large change in noise).
Noise induced hearing loss is permanent/temporary and caused what?
Temporary.
It is caused by over-exposure to noise at 90dB or more.
It causes a temporary damage to the membrane of the cochlea.
Discomfort in ear begins at __dB.
It becomes painful at __dB.
You can rupture an eardrum (temporary) at _dB.
Discomfort in ear begins at 120dB.
It becomes painful at 140dB.
You can rupture an eardrum (temporary) at 160dB.
Conductive Hearing Loss
What is it?
What can cause it?
It’s when we have a failure in teh sound conductive elements (ossicles/tympanic membrane).
Can be caused by:
- Trauma
- Too much wax
- Cold/Infection
- Damage to auditory nerve.
Presbycusis
What is it?
What causes it?
Which tones go first?
Hearing loss due to age.
High tones go first.
What is tinnitus?
Constant noise in ear (roaring, ringin, humming, buzzing).
What is linear acceleration and what is it detected by?
Linear acceleration is acceleration/deceleration in linear flight/Take off/landing.
It is detected by the otoliths (utricle/saccule)
What is Radial/Centripedal acceleration?
When we are experiencing rotation on an axis external to our body (e.g. spin)
What is Angular/Transverse acceleration and what is it detected by?
Rotation on axis internal to our body.
It is detected by the semi-circular canals.
Which acceleration has the biggest physiological effects on a pilot?
Radial/Centripedal Acceleration
+/- Gx
Forwards and backwards movement
-Gx = moving backwards
+Gx = moving forwards
+/- Gy
Sideways movement (lateral)
-Gy = left movement
+Gy = right movement
+/- Gz
Vertical movement
-Gz = downwards movement
+Gz = upwards movement
1 +Gz effects:
- Blood pools in lower part of body (legs)
- Increases our hydrostatic variation (difference between blood pressure in head and body
2 +Gz effects:
- body and limbs become harder to move
- can experience cramps in calf muscles
3 +Gz effects:
- Organs are displaced downwards
- Facial features displaced downwards
3.5 +Gz effects:
- Can experience gray out
- Rods are less effective (not enough O2 in rods)
4-5 +Gz effects:
- Trouble breathing.
- Diaphragm pushed downwards
- Respiration difficulties
>5 +Gz effects:
- Not enough blood in head –> blackout
- Loss of consciousness
- Can fracture vertabrae
How do you reduce the effects of +Gz?
- Tense muscles
- Anti G-suit
Effects of -Gz:
- decreases our hydrostatic variation (much blood in the head)
- Face can be bright red
- Eyes get red
- Organs forced up
- Facial feautures pushed up
- Reduces heart rate
- Causes red-out (sight goes red)
Body can withstand ____ -Gz
2-3 -Gz
Which has a greater effect on the body: -Gz or +Gz?
-Gz
Long term exposure to G forces is defined as:
more than 1 sec
Short term exposure to G forces is defined as:
less than 1 second
Factors that affect G-tolerance
- Smoking
- Hypoxia
- Stress
- Heat
- Obesity
- Fatigue
- etc.
Long term exposure to G forces:
relaxed person vs tensed person
relaxed person: +3.5G
Tensed person +7-8G
Short term exposure to G forces:
Vertical
Linear
Vertical:
+25Gz, -2 - -3Gz
Linear:
+45G
