Hearing And Balance Flashcards
Describe the basic anatomy of the ear.
Outer ear - external ear and eardrum
Middle ear - ossicles (malleus, incus stapes) and Eustachian tube
Inner ear - semi circular canals and cochlea.
Describe the effects of age induced hearing loss (presbycusis)
Loss of hearing that occurs over age, generally slow
Explain the effects of age induced hearing loss (8)
Difficult hearing Frequently asking to repeat Frustration Certain sounds overly loud Noisy areas S or th sounds the same Difficulty high pitch Tinnitus
Explain the effects of pressure changes on the middle ear and Eustachian tube.
Eustachian tube is normally closed but opens from time to time when we swallow, yawn or chew.
Allows air to flow into the middle ear and any mucus to flow out keeping air pressure equal either side of the eardrum.
Explain the effects of colds; hay fever; and/or allergies on the sinuses and eustachian tubes.
A blocked nose or thick mucus that develops during a cold or other infections may block the Eustachian tube causing an equal pressure.
Typically, with a blocked Eustachian tube, the air pressure in the ear canal is greater than the pressure in the middle ear.
With a reduced air pressure on one side, the ear drum or tympanic membrane bulges inward, causing discomfort and in some cases extreme pain.
Define disorientation
Cognitive disability in which the sense of time, direction and recognition of people and places become difficult to distinguish
Happen anytime
Define spatial orientation
Spatial orientation is defined as the ability to correctly interpret the aircrafts’ attitude, altitude and/or airspeed in comparison to Earth or a point of reference
Outline the physiology of the motion, orientation and gravitational sensory organs - semi-circular canals
Made of 3 canals, posterior (pitch) superior (roll) and horizontal (yaw)
Interlinked at right angles with each other and filled with liquid which shifts in relation with rotational acceleration of the body.
Outline the physiology of the motion, orientation and gravitational sensory organs, including vestibular sacs and tubes.
Two otolith organs, the utricle and saccule found in the vestibular sac.
Each organ has gelatinous substances surrounding har like cells which sense linear acceleration from the movement of the substance.
The otolith organs sense both head/body tilt and longitudinal acceleration.
Explain the interconnection between the visual and kinaesthetic senses in maintaining accurate spatial orientation.
Many thousands of never ending in the joints muscles and neck which generate information on movement and position
Called proprioceptors
Explain the body’s limitations in maintaining spatial orientation when vision is adversely affected
False info from either sense will normally be compensated for by the other.
In the absence of normal visual inputs, as when flying in could or at night incorrect information from the. Vestibular system can lead to pilot disorientation or motion sickness.
Explain the leans and sub-threshold stimulation
- a strong sensation felt by pilots as being in one attitude when all the aircraft instruments are indicating that the aircraft actually has a different altitude
- caused by slow rolling of the aircraft that’s not picked up by the semi-circular canals.
Explain somotogravic illusions.
Because the otolith can’t distinguish between a rapid longitudinal acceleration and a body/head tilt backwards, a powerful but erroneous sensation of a steep climb can occur in the event of a rapid takeoff.
Explain somotogyral illusion
Occurs when pilot has leans but isn’t aware, aircraft having meanwhile entered a spiral dive.
As speed builds, pilot beliefs the aircraft wings level dive and tries to pull out of the dive.
However aircraft has considerable bank applied so therefore this increases intensity of spiral dive.
Explain cross coupled turning (Coriolis effect)
the result of moving the head excessively, especially during in flight turns, confusing the balance mechanism in the ears.
can produce a tumbling sensation which may lead to nausea and disorientation.
Explain pressure vertigo
condition that occurs as a result of pressure differences between the ears. As aircraft climbs this higher pressure inside the eardrum can force its way out, but on descent, the higher pressure outside air cannot enter the blocked tubes leading to a pressure differential.
Pressure vertigo can occur when only one ear ‘pops’, which may cause a tumbling sensation and slight onset of vertigo
Prevention of disorientation.
- don’t fly an aircraft based on the ‘seat of your pants’ - e.g. what you think the aircraft is doing
- in periods of reduced visibility or at night, transition to scanning the instruments early (as required)
- fly at night and with instruments often to keep proficient
- use and trust your instruments
Explain the effects of a positive and negative acceleration on the circulatory system.
Positive G - the blood pressure in the head may fall to a point where blood supply to the eyes and brain ceases
Negative G - blood is forced upwards and can cause much greater discomfort than positive G, upward movement of blood can overload the heart, slowing it.
Explain the effects of positive and negative accelerations on vision
Positive G - visual acuity is reduced and therefore loss of peripheral vision with a retention of central vision (tunnel) prolonged acceleration above 5 can cause blackout
Negative G - blood is forced to head and eyelids. Bloood laden eyelids can come into visual field causing vision to be red. Redout
Explain the effects of positive and negative accelerations on consciousness
Positive G - +5 to +6g pilot may become unconscious. Due to blood being drained away form the brain and therefore also oxygen from the brain causing a type of hypoxia.
Negative G - if heart rate is slowed down to far this could lead to heart stopping
Causes and symptoms of blackout
- exposure to + 5g due to blood draining from head
- pilot will experience grey or tunnel vision first but continued exposure will lead to complex loss of vision. hearing is unaffected until unconscious.
Red out causes and systems
- Exposure to -2.5G or greater or blood is forced to the head and eyelids.
- Blood laden eyelids can come into the visual field causing vision to appear read.
Explain the causes of motion sickness
A normal response of healthy individuals when exposed to a flight environment characterised by unfamiliar motion
Explain how motion sickness can be prevented
Not flying with fatigue, after alcohol, drugs, medications, under stress or illness.
Repeated exposure to flight environment will usually decrease an individuals susceptibility.
Explain how motion sickness can be treated (5)
- Open all air vents
- Loosen clothing
- Use supplemental oxygen if available
- Focus on a point in the distance
- Avoid unnecessary head movements.
Causes of flight anxiety.
Develop fears as they mature and life seems to be more precious or bad previous experiences of flight.
Concerns regarding weather or fears.
Signs of flight anxiety (5)
- Muscle tension; tremors
- heavy, laboured breathing
- heart palpitations, chest pain
- abdominal & intestinal discomfort
- sweating, weakness, dizzy, prickly sensations, Dry mouth, flushed or pale face
Explain How flight anxiety be prevented (4)
- Attend a course and education
- Learn how they fly
- Learn how airliners are flown in practice
- skydive
What does the cochlea do?
Connected to the cochlear nerve, transmitting sound via neurological signals to the brain to produce the sound that is heard
34.20.10/46.20.6 The various levels of noise in decibels at which various grades of hearing protection are required
Over 115dbA - seek expert advise
110-115 - grade 5 earmuffs 104-109 - grade 4 98-103 - grade 3 92-97 - grade 2 86-91 - grade 1 85 and below - non needed
34.20.14/46.20.10 The action threshold for hearing protection
The action level for hearing protection is a level of noise exposure above which active steps should be taken in order to avoid the harmful effects of the noise on hearing
34.20.12/46.20.8 Noise levels at which hearing damage may occur
Temporary hearing impairment: steady noise over 90 dB over a short time (even several hours)
- Permanent hearing damage: noise over 90 dB for 8 hours or more per day for several years
- Immediate hearing loss: a sudden noise of 140 dB – 150 dB
c) G-LOC (gravity induced loss of consciousness)
Caused by prolonged exposure to +5 – 6g
- The pilot will lose consciousness until the amount of g-force is reduced.
- Recovery will be delayed by the fact that the blood has concentrated in the lower limbs where it does not readily return for re-circulation.
- Pilots of aircraft required to carry out high G manoeuvres wear special G suits which resist the pooling of blood.
Physiology of the ear
The ear has two functions: Performing Hearing and sensing Balance/Acceleration
●Sound waves travel through the ear canal and vibrate the air drum - this vibration transfers to the ossicles which in turn vibrates the cochlea. This causes fluid inside the cochlea to move which produces electrical signals that are transmitted to the brain.
●The signals are then processed and perceived as sound
How much protection do earmuffs and earplugs give you
10-15db
