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Tuning Fork Tests

References . Introduction to Audiology ? Chapter 2 (The Human Ear and Simple Tests of Hearing)Audiology Diagnosis ? Chapter 11 (Pure Tone Tests)Lecture Notes . Topics . Definition and Development of Tuning forksPrinciple of Tuning Fork TestsTuning Fork Tests Premise/PrincipleProcedureInte

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Tuning Fork Tests

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    1. Tuning Fork Tests Lecture 8 Tahani ALothman

    2. References Introduction to Audiology Chapter 2 (The Human Ear and Simple Tests of Hearing) Audiology Diagnosis Chapter 11 (Pure Tone Tests) Lecture Notes

    3. Topics Definition and Development of Tuning forks Principle of Tuning Fork Tests Tuning Fork Tests Premise/Principle Procedure Interpretation Advantages & Disadvantages Standard Tuning Fork Tests Vs. Pure Tone BC Test & Audiometric Tuning Fork Test

    4. Learning Objectives Upon completion of this class, the student should be able to: List and describe the available tuning fork tests Mention the advantages and disadvantages of each tuning fork test Describe the expected tuning fork tests results for different types of hearing loss.

    5. Tuning Fork Tests Tuning fork: a device usually made of steel, magnesium or aluminum that is used to tune musical instruments or by singers to obtain certain pitches It emits a tone at a particular pitch and has a clear musical quality It vibrates sinusoidally to generate a pure tone We can set it into vibration by holding the stem/handle in the hand and striking one of the tines against a firm but resilient surface When it vibrates properly, the tines move alternately away from and toward one another Several forks are available, each correspond to notes on the musical scale. At CAMS, we have the following frequencies (4096, 2048,1024, 512, 256, 128, 64) Hz

    7. Tuning Fork Tests Used before the development of audiometers with BC and the other sophisticated electronic devices A century ago, they were used as an instrument for testing hearing Now, its rarely used by audiologists They illustrate the principles involved in certain modern tests They are still used by many physicians in their everyday practice

    8. Principle of Tuning Fork Tests CHL (OE or ME Disorder) Sounds delivered to the ear via AC will be attenuated If the sound is delivered to the ear via BC, bypassing the OE & ME, then the sound will be heard normally assuming there is no disorder SNHL (OE & ME Are Free From Disorders) Sounds delivered to the ear via BC will be attenuated

    9. AC & BC Pathways

    10. Types of Tuning Fork Tests Standard Tuning Fork Tests Audiometric Tuning Fork Tests

    11. Standard Tuning Fork Tests Purpose: to diagnose the type of HL Results from these tests are determined by the presence or absence of an occlusion effect Schwabach Test Bing Rinne Weber

    12. Tuning fork stem is held against the mastoid bone behind the ear (A) - Tuning fork tines are held next the opening of the ear (B) Tuning fork stem is placed on the midline of the patients skull (forehead) (C)

    13. Schwabach Test Was once popular but no longer is in general use It compares pts hearing sensitivity with that of an examiner (assuming that he/she has a normal hearing) The fork is set into vibration, stem is placed alternately against the mastoid process of the pt. and of the examiner Pt. should indicate whether the tone is heard or not each time the fork is placed is pressed against his/her mastoid process Vibratory energy of the tines of fork decreases overtime, making the tone softer When the pt. no longer hears the tone, examiner immediately places the stem behind his or her own ear and using a watch, notes the number of seconds the tone is audible after the pt. stops hearing it

    14. Schwabach Test Normal Schwabach: Both pt. & examiner stop hearing the tone at approximately the same time Pt. has normal BC Pt. has normal hearing or CHL Diminished Schwabach: Pt. stop hearing the sound much sooner than the examiner Pt. BC is impaired Pt. has SNHL

    15. Schwabach Test Can be quantified by recording the number of seconds an examiner continues to hear the tone after a pt. has stopped hearing it Examiner hears the tone 10 sec longer than a pt. ? pt. hearing is Diminished 10 seconds If pt. has CHL, BC is normal and they are expected to hear the tone for at least as long as the examiner In some CHL, the pts hearing in the low-pitch range may appear better than normal, called Prolonged Schwabach Disadvantages: Difficulties in the administration and interpretation of test in cases of MHL plus it requires normal hearing by the examiner

    16. Bing Test Premise: Persons with Normal hearing and SNHL when they close off the opening of the ear canal, loudness of a tone presented by BC increases Occlusion Effect Observed primarily for low-pitched sounds Absent in pts. with CHL

    17. Bing Test Assesses the presence of CHL Tuning fork is placed on the pt.'s mastoid, while the ear canal is alternatively opened and closed by the examiner by depressing tragus and the pt. is asked to state which position is louder When the ear canal is closed on a person with normal hearing or SNHL, low-frequency bone conducted signals are heard more loudly (Occlusion Effect), the is a "Positive Bing Pts. with CHL will not experience this sensation and the tone will be the same when the ear canal is open and closed and the test will be a "Negative Bing" because the ear already has a conductive impairment

    18. Rinne Test Compares pts' hearing sensitivity by BC to their sensitivity by AC The tuning fork is set into vibration and held close the pt's ear Tuning fork is alternatively held to the ear and then the base is placed on the mastoid process pt. is asked to state where the tone is louder, at the ear or at the mastoid Pts. with normal hearing and SNHL will hear the tone louder at the ear (Because AC is a more efficient means of sound transmission to the IE than BC) than behind the ear (Positive Rinne) Pts. with CHL (more than mild) or MHL will hear the tone louder with the stem of the fork behind the ear because their BC hearing is better than their AC hearing (Negative Rinne)

    19. Disadvantages In Schwaback test, Bing test and Rinne Test: There is always a danger of getting a response to the tone by the non-test ear (especially if the BC of the non-test ear is more sensitive than the BC of the test ear ( False negative results may occur Give rise to improper diagnosis of CHL

    20. Weber Test A test of lateralization Used for pts. reporting unilateral HL The examiner places the stem of the tuning fork on the midline against the pt's forehead The pt. should state if the tone is heard in the left ear, right ear, both ears or in the midline Weber effect is based on Stenger Principle: If two tones are identical except they are different in loudness, are introduced simultaneously into both ears, only the louder tone will be perceived Two ears, one has poorer BC sensitivity, when the tone is being produced to both ears with equal energy, the tone will be perceived softer or will not be perceived at all in the poor ear

    21. If the tone lateralizes to the poorer ear: That ear has improved BC sensitivity CHL in the poor ear If the tone lateralizes to the better/good ear: The cochlea with the best hearing sensitivity will detect the signal SNHL or MHL in the poor ear If the sound is detected in the midline position: Normal hearing or equal amounts of the same type of HL in both ears (CHL, SNHL or MHL) If the sound lateralizes to the ear with greater conductive component: Pt. has a bilateral loss

    22. Weber Test Advantages: Quick Easy Often helpful Disadvantages: Difficult to interpret results in cases of unilateral CHL and MHL

    24. Standard Tuning Fork Tests Vs. Pure Tone BC Test & Audiometric Tuning Fork Test Standard Tuning Fork Tests Should never replace BC audiometry Advantages: Provides preliminary diagnosis of the type of HL Requires no special equipment Provide a quick way to validate PT audiometric data Easy to administer Frequently used by physicians

    25. Pure Tone Bone Conduction Test Regular BC pure tone audiometry test (bone conduction oscillator is placed on the patients mastoid) Advantages: More sophisticated than tuning fork tests Can replace standard tuning fork tests Provides greater intensity control over the stimulus Higher results reliability and validity

    26. Audiometric Tuning Fork Tests / Audiometric Weber Test Bone conduction oscillator is placed on the patients forehead Regular bone conduction pure tone audiometry at 500, 1000, 2000 & 4000 Hz Tone is raised above the pts hearing threshold Pt. is asked to indicate whether he/she hear each tone in the left ear, right ear or in the midline Tone will lateralizes to the poorer ear in case of CHL Tone will lateralizes to the better ear in case of SNHL Midline or unlaterlization in case of symmetrical loss or normal hearing Advantages: Can replace standard tuning fork tests Provides greater intensity control over the stimulus Higher results reliability and validity

    27. B. Forehead BC Placement

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