A & P Auditory Physiology 2009 Slideshow

1,614 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,614
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
66
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

A & P Auditory Physiology 2009 Slideshow

  1. 1. Anatomy and Physiology of the Speech and Hearing Mechanisms: Auditory Physiology<br />Wilhelmina Wright-Harp, Ph.D.<br />Associate Professor<br />Department of Communication <br />Sciences and Disorders<br />Howard University<br />2009 Fall Semester<br />
  2. 2. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Auditory Physiology<br />Organizing Principles of Hearing Physiology:<br />The external ear collects sound (acoustic energy) and shapes its frequency components;<br />The middle ear matches the air-borne acoustic signal, transforms it into mechanical energy, with the fluid medium of the cochlea;<br />The inner ear performs spectral and temporal analyses on the acoustic signal;<br />The auditory pathway conveys and processes the signal;<br />The cerebral cortex interprets the signal.<br />
  3. 3. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Auditory Physiology<br />The ear is capable of responding to:<br />Frequencies ranging from 20 to 20,000 Hz<br />Intensities ranging from 1 to 10 trillion.<br />
  4. 4. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />External Ear: Acoustic System<br />The auricle:<br />serves as a “sound funnel” by channeling acoustic energy into the EAM.<br />Aids in localization of sound<br />The EAM:<br />funnels sound to the TM.<br />functions as a closed tube resonator.<br />
  5. 5. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Middle Ear: Mechanical System<br />The middle ear:<br />Functions to convert acoustic energy into mechanical energy.<br />Serves as an impedance-matching device. Impedance-matching is achieved through two mechanisms:<br />Area effect<br />Lever effect<br />
  6. 6. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Inner Ear: Vestibular Mechanism<br />The inner ear is comprised of two divisions:<br />Vestibular Mechanism<br />The semicircular canals help maintain balance.<br />Provide input to the proprioceptive system<br />Aids in perception of body position<br />
  7. 7. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Inner Ear: Auditory Mechanism<br />The cochlea is designed to:<br />sort out the frequency components of an incoming signal, <br />determine their amplitude, and <br />identify basic temporal aspects of that signal.<br />
  8. 8. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Inner Ear: Hydraulic System<br />Hydraulic energy results from movement of the stapes footplate in and out against the perilymph in the oval window of the vestibule. <br />
  9. 9. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Inner Ear: Auditory Mechanism<br />The frequency analysis ability of the basilar membrane is influenced by three variables:<br />Graded Stiffness<br />Graded Mass<br />Graded Width<br />
  10. 10. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Inner Ear: Auditory Mechanism<br />Von Bekesy’s research revealed that the vibration is transmitted along the basilar membrane as a traveling wave.<br />As the traveling wave moves along the basilar membrane, it builds to a peak and then ends abruptly. <br />The cochlea has a tonotopic arrangement.<br />
  11. 11. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Inner Ear: Auditory Mechanism<br />Excitation of hair cells of the cochlea.<br />The inner hair cells are excited by fluid flow and turbulence of endolymph.<br />The outer hair cells are excited by shearing effect on the cilia.<br />Movement of the hair cells generates a neural impulse.<br />
  12. 12. W. Wright-Harp, Ph.D.<br />2002 Fall Semester<br />Neural Pathway of CN VIII<br />Pfeiffer (1966) described six different types of neural responses to auditory stimulation:<br />Single-unit response<br />Primary-like <br />Onset<br />Chopper<br />Pausers<br />Build-up<br />

×