Noise

Question 1

What are the 4 points of vulnerability in the cochlea?

Answer 1

• Lateral wall of the stria vascularis
• Stereocilia
• Pillar cells
• Inner hair cells and auditory nerve fiber junctions

Question 2

What is the long-term damage caused by noise in the cochlea?

Answer 2

• Secondary metabolic disruption that continues to develop days to week following noise exposure
• Large amounts of glutamate to be released into the synapses of Type I auditory nerve fibers
• Swelling of postsynaptic cell bodies and dendrites
• Delayed loss of cochlear ganglion cells

Question 3

What do reactive oxygen species damage?

Answer 3

• Organ of Corti
• Degeneration of spiral ganglion neurons
• Alterations in auditory cortex pathways

Question 4

How does noise affect speech perception?

Answer 4

• Affects synaptopathic mechanisms
• Reduces temporal processing skills
• Reduced temporal processing skills occurs b/c of the affected connections between the inner hair cels and low spontaneous rate auditory nerve fibers, which are essential to auditory processing

Question 5

What are the 4 points of intervention for pharmaceutical agents?

Answer 5

• Restore balance between ROS and other molecules
• Limit lipid peroxidation in the cochlea
• Maintain cochlear blood flow during and after noise exposure
• Intervene in cell death pathways

Question 6

What is lipid peroxidation?

Answer 6

The process by which free radicals and ROS target lipid molecules within the cochlea.

Lipids are major components of cell membranes

Question 7

What are the 4 ways to maintain cochlear blood flow during and after noise exposure?

Answer 7

• Increase cardiac output throughout the entire body
• Dilating cochlear blood vessels
• Thinning the blood by expanding plasma content
• Making blood cells more flexible

Question 8

What is apoptosis?

Answer 8

• Cell death pathway that requires a persistent energy supply
• The cell shrinks in dark cytoplasm and becomes a pyknotic nucleus with an intact plasma membrane

Question 9

What is necrosis?

Answer 9

• The passive cell death pathway that is linked to energy deprivation
• Cells become swollen and will rupture
• The residual material is ingested by neighboring cells

Question 10

What is the “ghost” pathway?

Answer 10

• Cells are broken down and lose their membranes

- The residual material maintains the shape of the once existing outer hair cell with a nucleus deficient in nucleoplasm

Question 11

What are the goals of a noise conservation program?

Answer 11

• Measure the noise
• Reduce the noise if the levels measured have exceeded permissible levels
• Provide education to employers and employees
• Monitor hearing
• Assess effectiveness of the program