SOUND

2. SOUND Sound is energy comprising of compressional waves. Each wave of compression is followed by a rarefaction.

3. SOUND INTENSITY is the measure of power in terms of dynes/cm2 or on logarithmic scale in terms of bels and decibels. The perception of intensity is loudness.

4. SOUND FREQUENCY is the number of waves passing at a particular point in one second. This reflects the wavy pattern. The perception of frequency is the pitch. The higher is the frequency, the higher is the pitch and more shrill is the sound. The lower is the pitch, the more bass is the sound.

5. PATHWAY OF SOUND Air Pinna EAM Tymp. Membrane Ossicles Footplate of stapes Scala vestibuli and tympani Hair cells. Cochlear nerve. Cochlear N. nucleus Superior olivary complex. Lateral lemniscus Inferior colliculus Auditory area of cerebral cortex.

10. TRANSMISSION OF SOUND Pinna, external auditory meatus � condution only. Middle ear � conduction and impedance matching. Internal ear � Dampening and Conversion into electrical signals. Cochlear nerve and beyond � Transmission as electrical signals.

12. HEARING TESTING AIR CONDUCTION BONE CONDUCTION

13. HEARING IMPAIRMENT CONDUCTIVE DEAFNESS SENSORINEURAL DEAFNESS

14. FACTS IN T.F. TESTS Air conduction is normally better than the bone conduction In conductive deafness bone conduction not only relatively improves than the air conduction but absolutely improves as compared to the bone conduction of a normal ear. In S.N.Deafness both the air and bone conduction decrease but air conduction is still better than the bone conduction

15. RINNIE TEST In rinnie test we compare the air conduction with the bone conduction

16. RINNIE TEST LOUDNESS COMPARISON METHOD Patient is asked to compare the loudness of Air conduction with bone conduction LOUDNESS DECAY METHOD Patient is asked to assess the sound after complete decay

20. RINNIE TEST FINDINGS RESULT INFERENCE AC>BC R+VE 1)Ear is normal 2)Ear is having S.N. Deafness BC>AC R-VE Ear is having Conductive deafness

21. WEBER TEST In Weber test we compare the bone conduction of the two ears simultaneously.

22. WEBER TEST The tuning fork is struck and placed in the midline of skull e.g. vertex, forehead, teeth, chin. The patient is asked to indicate whether he hears the sound in the centre, in right ear or left ear

26. WEBER TEST FINDINGS RESULT INFERENCE Patient hears W-central Both the ears Better in centre are normal Both the ears are diseased to the same extent Patient hears better W-RE 1-Right ear is having In Right Ear conductive deafness 2- Left ear is having S.N. Deafness or both Patient hears better W-LE 1-Left ear is having In Left Ear conductive deafness 2- Right ear is having S.N. Deafness or both

27. ABC TEST In ABC test we compare the absolute bone conduction of the patient's ear with that of a normal ear.

28. ABC TEST The tuning fork is struck and placed on the mastoid process of the patient's ear and the ear is blocked. Patient is asked to indicate when the sound is completely abolished. The tuning fork is then shifted to the examiner's mastoid and the ear is blocked.

30. ABC TEST FINDINGS RESULT INFERENCE Examiner hears ABC-Shortened Patient is the sound on patient having S.N.D Examiner does ABC-Equal Patient is not Not hear the Having S.N.D sound