Audiometry

Principle, Applications and functions of audiometer

1. By : Imtiaz ur Rehman 4 th Year MBBS Khyber Medical College Peshawar AUDIOMETRY

2. AUDIOMETRY DEFINITION Audiometry is a procedure which is performed to measure hearing acuity and also to detect hearing disabilities.

3. It is more precise than tuning fork tests. It is quantitative. It determines hearing acuity. Performed with an audiometer. CHARACTERISTICS

4. HEARING ACUITY Hearing acuity means the lowest level of intensity at which a person can hear a particular tone or frequency.

5. Headphones are applied to a subject’s ears and at a specific frequency, sound of different intensities are checked. PRINCIPLE

6. Subject Comfortable chair Red and blue markers Audiometer Audiogram REQUIREMENTS

7. AUDIOMETER Device used to perform audiometry.

8. PARTS OF AUDIOMETER Output Selector Switch Intensity Knob Tone Interrupter Frequency Knob Battery Indicator Headphones Adaptor

9. Graphical representation of those frequencies and intensities which are audible to subject. AUDIOGRAM

10. Ask the subject to sit comfortably on a chair. Explain the full procedure to subject. Place the headphones on the subject’s ears. (Red  Right , blue  Left) Ask the subject to raise his left or right hand whenever he/she listens to sound. Fix the frequency and increase loudness. PROCEDURE

11. When subject raise his/her hand,note that loudness. Now decrease the loudness by 5db and then increase by 5db for confirmation. Bring the loudness knob back to 0db mark. Change the frequency and again increase the loudness.

12. Check response of subject at different frequency Repeat the procedure for both ears.

13. Patient must be well aware of the procedure. Room should be Sound proof and quiet. Glasses, ear rings and any other metallic objects (if present) should be removed. Hearing aids (if present) should be removed. The subject should not face the front panel of the audiometer. PRECAUTIONS

14. Head phone must be applied properly (red to right and blue to left). Leads must be properly attached (red to right and blue to left).

15. Clinical Points

16. 18-25 years age. No deafness before this age. No wax in ear. No exposure to noise Conditions for normal hearing

17. Degrees of Hearing Loss

18. Sound Intensities of different objects

19. DISEASES

20. It is the defect in the conduction of sound waves in the inner ear. It is mainly caused by the wax or any damage to ear drum. 1. Conductive Deafness

21. Audiogram for Conductive Deafness

22. It is a defect in which there is damage to cochlear hair cells or auditory pathway. It is mainly caused by damage to VIII nerve or auditory pathways. 2. Sensorineural Deafness

23. Mild Deafness Audiogram for sensorineural deafness Moderate Deafness

24. In this condition the hearing loss is almost same in both ears. 3. Symmetrical Hearing Loss

25. Audiogram for symmetrical hearing loss

26. In this condition the hearing loss is different in both the ears. 4. Asymmetrical Hearing Loss

27. Audiogram for Asymmetrical hearing loss

28. This is the condition of hearing loss due to increasing age due to damage to the base of cochlea. 5. Presbyacusis

29. Audiogram for Presbyacusis

30. In this condition the loud noise cause damage to cochlea. 6. Noise-Induced Deafness

31. Audiogram for Noise-induced deafness

32. Also called as middle ear sclerosis. It is a heredity disorder. There is fibrosis in middle ear cavity. In some cases there is a bony outgrowth from stapes so the foot-plate become stiffed. There is no conduction of sound from tympanic membrane to inner ear. 7. Otosclerosis

33. Audiogram for otosclerosis

34. Thanks !!!