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A “Deafinite” Cause for Alarm

A Case Study in Hearing Physiology


Rebecca T. Garlinger
Department of Biology
Villanova University
Patrick K. Mitrano-Towers
Department of Biology
Villanova University
Kevin S. Innella
Department of Biology
Villanova University
Philip J. Stephens
Department of Biology
Villanova University


“Henry” is not the best of patients. He has been admitted into the hospital with bacterial pneumonia, but he soon becomes bored and frustrated by his rate of progress; are the prescribed intravenous antibiotics really doing anything? His solution is to take matters into his own hands and increase the rate of antibiotics perfusion with the idea that increasing his dose will cure him faster and hasten his discharge from the hospital. The consequences are not good. During convalescence at home, “Freddie,” Henry’s son, discovers that his father is losing his hearing. In working through this case study, students will discover how sound waves stimulate the hair cells in the cochlea and produce the sensation of hearing. This case was designed for use in a one-semester animal physiology course taken by sophomore and junior science majors; it could also be used in an anatomy and physiology course.


  • Describe how sound entering the ear stimulates hair cells in the cochlea.
  • Explain how movement of the stereocilia changes the membrane potential of the hair cells by opening and closing potassium channels.
  • Describe how changes in the membrane potential change the transmitter output from the hair cells.
  • Explain how changes in the flexibility of the basilar membrane allow frequency discrimination.
  • Identify how damage to hair cells in certain regions of the cochlea can produce tone deafness.


Ear; cochlea; hearing; frequency discrimination; stereocilia; potassium channels;

Topical Areas


Educational Level

High school, Undergraduate lower division



Type / Methods




Subject Headings

Biology (General)  |   Physiology  |   Medicine (General)  |   Neuroscience  |   Zoology  |  

Date Posted


Teaching Notes

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Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.

Supplemental Materials

The PowerPresentation below can be used to project two images in the case as described in the teaching notes.

  hair_cells.pptx (~5MB)

Answer Key

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The following video(s) are recommended for use in association with this case study.

  • 2-Minute Neuroscience:The Cochlea
    This video discusses the cochlea. Sound waves pass through the ear and lead to the depression of the oval window, a structure found in the wall of the cochlea. The effect of these movements on sensory elements within the cochlea are described. Running time: 2 min. Produced by Neuroscientifically Challenged, 2015.
  • The Hair Cell
    This animation (MP4 format, ~4MB) ) illustrates how auditory hair cells detect motion. Running time: 1:39 min. Produced by Phil Stephens, case study co-author.