Biol 1152l name Ear, Hearing, Equilibrium Day & Lab time Written by Dr. Diane Day Pre-Lab Exercise

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Biol 1152L Name ________________________________________

Ear, Hearing, Equilibrium Day & Lab time _______________________________________

Written by Dr. Diane Day

You should be familiar with the following terms before coming to lab. Look up the functions of each of the following structures.

Auricle (pinna) ________________________________________________________________________
External auditory meatus (canal) __________________________________________________________
Tympanic membrane ___________________________________________________________________
Auditory ossicles _______________________________________________________________________
Eustachian tube _______________________________________________________________________
Vestibule _____________________________________________________________________________
Semicircular canals _____________________________________________________________________
Cochlea ___________________________________________________________________________
Oval Window __________________________________________________________________________
Round Window ________________________________________________________________________

In-Lab Exercise

  1. Outer ear 3. Inner ear

  1. Auricle (pinna) a. Vestibule

  2. External auditory meatus (canal) i. Saccule

  1. Middle ear ii. Utricle

    1. Tympanic membrane b. Semicircular canals

    2. Ossicles i. Semicircular duct

      1. Malleus ii. Ampulla

      2. Incus c. Cochlea

      3. Stapes i. Organ of Corti

    3. Oval window ii. Cochlear duct

    4. Round window d. Vestibulocochlear nerve

    5. Eustachain (auditory) tube i. Vestibular nerve

  2. Inner ear ii. Cochlear nerve

Table 1: Ear Model Inventory


Structures Identified

II. Lab Exercises: Hearing

Two clinical tests are used to determine hearing loss, the Weber test and the Rinne test. Conductive hearing loss results from interference of sound conduction through the outer and/or middle ear. Sensorineural hearing loss results from damage to the inner ear or the vestibulocochlear nerve. A tuning fork is placed directly on the bones of the skull to evaluate bone conduction, the ability to hear the vibrations transmitted through the bone. The fork is then placed near the ear, not touching bone, to evaluate air conduction, the ability to hear the vibrations transmitted through the air.

Review the principles behind these two tests.
Weber Test
1. Obtain a tuning fork with a frequency of 500-1,000 Hz.

2. Hold the tuning fork by the base, and strike it lightly. The fork should begin ringing softly. If it is ringing

too loudly, grasp the tines to stop it from ringing, and try again.

3. Place the base of the vibrating tuning fork on the midline of your partner’s head.

4. Ask your partner if the sound is heard better in one ear or if the sound is heard equally in both ears. If

the sound is heard better in one ear, this is called lateralization.

Was the sound lateralized? If yes, to which ear? _____________________________

5. To illustrate what it would sound like if the sound were lateralized, have your partner place his or her finger in one ear. Repeat the test.

  1. In which ear was the sound heard better? __________________

  2. If a patient has conduction deafness, in which ear do you think the sound will be heard most clearly (the deaf ear or the good ear)? ______________________________ Why? (If you are confused, think about your results when one ear was plugged.) ________________________________________________________________________________________________________________________________________________________________

  3. If a patient has sensorineural deafness, in which ear do you think the sound will be best heard? _____________________________________________________________________

Rinne Test
1. Strike the tuning for lightly to start it ringing.

2. Place the base of the tuning fork on your partner’s mastoid process.

3. Time the interval during which your partner can hear the sound. Your partner will have to tell you

when he or she can no longer hear the ringing.

Time interval in seconds: ___________________________________________________

4. Once your partner cannot hear the ringing, quickly move the still-vibrating tuning fork 1-2cm lateral to

the external auditory canal (the fork should not be touching your partner at this points).

5. Time the interval from the point when you moved the tuning fork in front of the external auditory

canal to when your partner can no longer hear the sound.

Time interval in seconds: ______________________________

Which situation tested bone conduction? _______________________________

Which situation tested air conduction? _________________________________

6. Typically, the air-conducted sound is heard twice as long as the bone-conducted sound. For example,

if the bone-conducted sound was heard for 15 seconds, the air-conducted sound should be heard for

30 seconds.

Were your results normal? _____________________________________________________

What type of deafness is present if the bone-conducted sound is heard longer than the air-conducted

sound? _________________________________________________________

Critical Thinking
Otosclerosis is a condition that results in irregular ossification (bone formation) around the stapes bone. Would you expect this to result in conductive or in sensorineural hearing loss? What results would you expect from the Rinne and Weber tests in an individual with otosclerosis?

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