Principle, Applications and functions of audiometer

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

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

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

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

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

7.  Subject
 Comfortable chair
 Red and blue markers
 Audiometer
 Audiogram

8. Device used to perform audiometry.

10.  Graphical representation of those frequencies and
intensities which are audible to subject.

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

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

13. 10. Check response of subject at different frequency
11. Repeat the procedure for both ears.

14.  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.

15.  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).

17.  18-25 years age.
 No deafness before this age.
 No wax in ear.
 No exposure to noise

21.  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.

23.  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.

24. Mild Deafness Moderate Deafness

25.  In this condition the hearing loss is almost same in
both ears.

27.  In this condition the hearing loss is different in both
the ears.

29.  This is the condition of hearing loss due to increasing
age due to damage to the base of cochlea.

31.  In this condition the loud noise cause damage to
cochlea.

33.  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.