Ch 7 - The Ear, Hearing And Balance

Question 1

Three distinct sections of the human ear

Answer 1

The outer ear - AIR

The middle ear - AIR

The inner ear - LIQUID

Question 2

Pinna

Answer 2

Visible part of the ear

Question 3

Ear Canal

Answer 3

Channels the sound waves to the ear drum

Question 4

Ear Drum (tympanic membrane)

Answer 4

Separates the outer and middle ear, sound waves make the ear drum vibrate

Question 5

Ossicles

Answer 5

3 Bones: (smallest bones in the body)

• Malleus (hammer)
• Incus (Anvil)
• Stapes (stirrup)

The 3 bones pick up vibrations from the ear drum and pass them to the inner ear

Question 6

The Vestibular System

Answer 6

3 Semi-circular canals measuring angular accelerations; Yaw, Pitch and Roll (can lead to illusions)

Otoliths:
Made up of; Utricle and Saccule

They sense linear accelerations

Question 7

Cochlea

Answer 7

(Snail)

Filled with fluid.

Vibrations in the cochlea are received through either the outer/middle ear or the skull by skull conduction

Question 8

Auditory Nerve

Answer 8

Information from the cochlea is detected by the auditory nerve, which leads directly to the cortex of the brain

Question 9

Eustachian tube

Answer 9

Connected to passage of nose and throat and equalises pressure between the outer (atmospheric) pressure and the inner ear pressure.

Linked to otic barotrauma

Question 10

Cerebellum

Answer 10

Receives vestibular information about balance and acceleration

Question 11

Audible range and measurement

Answer 11

Average adult human ear:
20Hz - 20,000Hz

Most sensitive to: 750-4000Hz (speaking tones)

Sound is measured in decibels. Decibels are a non-linear, logarithmic scale which means the a small change in the number could be a big change in the volume.

• High tone, intermittent sounds induce the most adverse affect on performance

Question 12

Noise Induced Hearing Loss

Answer 12

At 90dB - you can start to have noise induced hearing loss if exposed to for a while

• Temporary - caused by damage to the membrane of the cochlea
• How long depends on; Intensity, frequency, duration exposure
• If frequently exposed, it can lead to permanent loss of hearing

120dB - Discomfort in the ear

140dB - Painful

160dB - Rupture ear drum

Question 13

Conductive Hearing Loss

Answer 13

Conductive hearing loss is when the sound conducting elements of the ear are not working properly. Could be any of the following or a combination:

Cochlea
Auditory nerve
Ossicles
Excessive amounts of wax in the ear canal
Ruptured ear drums

Question 14

Presbycusis

Answer 14

Loss of hearing with age.

High tones go first, with sensitivity to those levels decreasing (especially being on a flight deck)

Question 15

Tinnitus

Answer 15

Constant ringing/sound that can be heard in the ear