Acoustic analyzer

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Acoustic analyzer

  1. 1. PHYSIOLOGY and METHODS of EXAMINATION of the ACOUSTIC ANALYZERS
  2. 2. The acoustic analyzer <ul><li>Each analyzer is a physiological transformer of the energy of an external stimulation into a nervous process </li></ul>
  3. 3. The main rules of acoustic analyzer <ul><li>It has definite frequency range of the sounds. </li></ul><ul><li>The sensitiveness of the different frequency is not equal. </li></ul><ul><li>A person can determine the absolute pitch of tone. </li></ul><ul><li>A person can determine the source of sound location (ototopika) </li></ul>
  4. 4. The acoustic analyzer <ul><li>The acoustic analyzer is divided into three parts: the peripheral section, the pathway and the cortex zone. </li></ul><ul><li>The peripheral section consists of the sound-conducting and sound-perceiving parts. </li></ul>
  5. 5. The sound-conducting part <ul><li>The outer ear – </li></ul><ul><li>the eardrum – </li></ul><ul><li>the ossicles – </li></ul><ul><li>the oval window – </li></ul><ul><li>the perilymph – </li></ul><ul><li>the endolymph of the inner ear – </li></ul><ul><li>the basilar membrane. </li></ul>
  6. 6. The sound-perceiving part - the sound transforms into nerve impulse
  7. 7. <ul><li>Pathways: </li></ul><ul><li>The spiral ganglion (the body of the first neuron) </li></ul><ul><li>the eight nerve – the nucleus of the medulla (the body of the second neuron) </li></ul><ul><li>brain bridge – olive (the body of the third neuron) </li></ul><ul><li>the midbrain – the geniculate body (the body of the forth neuron). </li></ul>
  8. 8. Cortex zone <ul><li>The temporal lobe of brain is the cortex zone of acoustic analyzer. </li></ul>
  9. 9. The middle ear mechanism <ul><li>The sound protection (the function of the screen) </li></ul><ul><li>The sound transformer mechanism </li></ul>
  10. 10. Air and bone conduction <ul><li>The cochlea can be stimulated directly by bone conduction as well as by sound passing through the middle ear. </li></ul>
  11. 11. Conductive hearing loss <ul><li>The results from any interruption to the passage of sound </li></ul>
  12. 12. Sensori-neural hearing loss <ul><li>The damage of the cochlea or the upper parts of analyzer </li></ul>
  13. 13. Mixed hearing loss
  14. 14. Methods of examination <ul><li>Examination of the hearing with help of whisper speech . </li></ul><ul><li>Examination of the hearing with help of ordinary speech . </li></ul><ul><li>Tests with help of tuning forks (experiments performed by Rinne, Veber, Schwabach). </li></ul><ul><li>Pure-tone, speech and game (in childhood) audiometry . </li></ul>
  15. 15. Examination of the hearing with help of speech <ul><li>Normal human ear must hear sounds of whisper speech on 6-meter distance and more. And it must hear sounds of ordinary speech on 20-meter distance and more. </li></ul>
  16. 16. Tuning forks <ul><li>These are the instruments generating the sounds of certain frequency. </li></ul>
  17. 17. Rinne’s test.
  18. 18. Rinne’s test – the comparison between air and bone conduction Air > Bone Air < Bone Positive - Normal Perceiving hearing loss Negative - Conductive hearing loss
  19. 19. Weber’s test.
  20. 20. Weber’s test Normal hearing Normal hearing
  21. 21. Weber’s test - lateralized to the health side Normal hearing Perceiving type of hearing loss
  22. 22. Weber’s test - lateralized to the sick side Normal hearing Conductive type of hearing loss
  23. 23. Schwabach's test.
  24. 24. Schwabach's test. Perceiving type of hearing loss Conductive type of hearing loss elongated shortened
  25. 25. The difference between two types of hearing loss Shortened Schwabach’s test Elongated Lateralization to the healthy ear Weber’s test Lateralization to the sick ear Positive Rinne’s test Negative Sensori-neural hearing loss Test Conductive hearing loss
  26. 26. The audiometer <ul><li>The usual way of recording hearing is by the audiometer, of which there are two types: pure-tone and speech. </li></ul><ul><li>There are two ways to conduct sound to the inner ear: air conduction and bone conduction. Each audiometer has ear-phones for air conduction and bone microphone for bone conduction. So the audiogram consists of two curves (air and bone conduction). </li></ul>
  27. 27. Pure-tone audiometry
  28. 28. <ul><li>Normal hearing – </li></ul><ul><li>Thresholds from 0 to 10 dB for all frequencies </li></ul><ul><li>There is no difference between air and bone curves. </li></ul>
  29. 29. Characteristic of the audiogram in case of conductive hearing loss: <ul><li>Reduced perception of low tones by air. </li></ul><ul><li>Normal perception of all tones by bone. </li></ul><ul><li>There is a bone-air gap </li></ul>
  30. 30. Characteristic of the audiogram in case of sensori-neural hearing loss <ul><li>Reduced perception of high tones by air and by bone. </li></ul><ul><li>The threshold by air and by bone are increased equally . </li></ul><ul><li>There is no bone-air gap. </li></ul>
  31. 31. Characteristic of the audiogram in case of mixed hearing loss <ul><li>Reduced perception of high tones by air and by bone. </li></ul><ul><li>Reduced perception of low tones by air but normal perception of low tones by bone. </li></ul><ul><li>There is a difference between air and bone conduction (bone-air gap). </li></ul>

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