7: Auditory System

Question 1

What is Sound Composed of?

Answer 1

• Acoustic waves
• It’s the vibration of air molecules at a high frequency (waves/ sec)
• Concentric waves = compression & rarefraction

Question 2

What’s the Function of the Eustachian Tube?

Answer 2

• Throat to middle ear passage
• For pressure equalization b/w outer & middle ear
• -Pressure = +/- pain/ difficulty w altitude
• Yawn/ swallowing = opens tube & relieves pressure
• Bulging in/ out of tympanic memb = pain/ pressure
• -Eustachian tube helps this!

Question 3

Explain the Attenuation Reflex Muscles.

Answer 3

Two Small Muscles: Tensor Tympani & Stapedius

• When they contract, they break vibration of ossicles
• -Reduces sensed vibration in ear
• -Contract when you talk! This way your voice isn’t too loud for you
• –Is a reflex loop

Question 4

How is Pressure Amplified in the Middle Ear?

Answer 4

Through 2 Mechanisms:

1. The oval window is much smaller than the tympanic membrane, so equal force is funnelled to a smaller area, increasing pressure!
   - Need higher pressure @ oval window to push fluid
2. The stapes displaces the oval window w about 1/10 displacement of the tympanic membrane, but much greater force!
   - The ossicles are a lever system