BearCh11-ACRQedt - Chapter 11 The Auditory and Vestibular...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 11 – The Auditory a nd Vestibular Systems Answers to Chapter Review Questions Page 1 of 6 Copyright © 2007. Lippincott Williams & Wilkins. Ancillary material to accompany Bear et al.: Neuroscience: Exploring the Brain, 3e Question 1: How is the conduction of sound to the cochlea facilitated by the ossicles of the middle ear? Answer: Sound waves traveling through air move the tympanic membrane, which, in turn, moves the ossicles. These transfer the movement of the tympanic membrane to the oval window, and the movement at the oval window vibrates the fluid in the cochlea. However, the fluid in the inner ear resists movement more than air does, so greater pressure is needed to vibrate the fluid. The ossicles amplify the pressure. The surface area of the oval window is smaller than that of the tympanic membrane, and the force is greater at the oval window than at the tympanic membrane because the ossicles act as levers. Because of these two mechanisms, the pressure at the oval window is about 20 times greater than the pressure at the tympanic membrane. This increase in pressure is sufficient to move the fluid in the inner ear. The movement of fluid in the cochlea causes a response in sensory neurons. Question 2: Why is the round window crucial for the function of the cochlea? What would happen to hearing if it suddenly didn’t exist? Answer: The round window is a membrane located at the base of the cochlea. When the ossicles move the membrane that covers the oval window, the inward movement at the oval window pushes the perilymph into the scala vestibuli. This increases the fluid pressure on the oval window, pushing the membrane at the round window outward. A complementary motion at the round window accompanies any motion at the oval window. This movement is crucial because the cochlea is filled with incompressible fluid held in a solid bony container. If it were absent, the fluid in the cochlea would not move in response to pressure at the oval window and the auditory receptors would not be stimulated.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chapter 11 – The Auditory a nd Vestibular Systems Answers to Chapter Review Questions Page 2 of 6 Copyright © 2007. Lippincott Williams & Wilkins. Ancillary material to accompany Bear et al.: Neuroscience: Exploring the Brain, 3e Question 3: Why is it impossible to predict the frequency of a sound wave simply by looking at which portion of the basilar membrane is the most deformed? Answer: Frequency must be coded in some way other than the site of maximal activation in tonotopic maps for two reasons. First, tonotopic maps in the central auditory pathways do not contain neurons with low characteristic frequencies — below 200 Hz — so there must be some other way to distinguish them. Second, something other than tonotopy is needed because the region of the basilar membrane maximally displaced by sound depends on its
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

BearCh11-ACRQedt - Chapter 11 The Auditory and Vestibular...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online