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AUDIOGRAM AND IMMITTANCE TUTORIAL

Presented by: Candice “Evie” Ortiz, AuD. AUDIOGRAM AND IMMITTANCE TUTORIAL. Conduction of Stimuli. Air Conduction Signals are delivered through the outer, middle and inner ears Further processing in the CANS Bone Conduction Signal delivered to the mastoid bone

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AUDIOGRAM AND IMMITTANCE TUTORIAL

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  1. Presented by: Candice “Evie” Ortiz, AuD AUDIOGRAM AND IMMITTANCE TUTORIAL

  2. Conduction of Stimuli • Air Conduction • Signals are delivered through the outer, middle and inner ears • Further processing in the CANS • Bone Conduction • Signal delivered to the mastoid bone • Bypasses the conductive mechanism • Stimulates both cochlea simultaneously

  3. Masking • Used to obtain accurate thresholds when cross-hearing is likely • Asymmetrical hearing losses of ≥ 40dB or ≥60dB • Dependent on transducers • Gaps of ≥ 15dB during BC • Non-test ear is kept “busy” by the introduction of a masking noise

  4. Basics of the Audiogram

  5. Classification of Hearing Loss • Normal: -10 to 25 dB • Mild: 26 to 40 dB • Moderate: 41 to 55 dB • Moderately-Severe: 56 to 70 dB • Severe: 71 to 90 dB • Profound: > 90 dB Picture Adapted from: Bess, F.H., Humes, L.E., Audiology: The fundamentals, 2003.

  6. Common Audiometric Configurations

  7. Type of Hearing Loss • Sensorineural (SNHL) • No air-bone gaps • ≥15 dB gap between AC and BC thresholds • Conductive (CHL) • ≥15dB air-bone gap • Consistent with middle ear pathology • Maximum conductive component is 60dB

  8. Describing a Hearing Loss • Degree, Configuration, Location, Type • Examples • Mild to severe sloping SNHL • No location implies that loss affects all frequecies • Severe high frequency SNHL • Moderate to mild rising low frequency CHL

  9. Describing Hearing Loss Examples

  10. Essentially Mild Profound

  11. Normal

  12. Mild to Moderate Normal

  13. Describing Hearing Loss Time for Practice Turn to Handouts

  14. What Does It Mean for Speech?

  15. Familiar Sounds Audiogram

  16. Not Audible

  17. SAT, SRT, and WRS Speech Testing

  18. Speech Audiometry • Speech Recognition Threshold (SRT) • Adults • Speech Awareness Threshold (SAT) • Infants and Non-Verbal patients • Useful in determining test reliability • Malingering • Does not understand task

  19. Reliability Determination Examples

  20. PTA = 3 PTA = 35 Good SRT-PTA agreement Good SRT-PTA agreement

  21. PTA = 10 PTA = 35 Good SRT-PTA agreement Poor SRT-PTA agreement

  22. Clinical Application ofWord Recognition Tests • Determine site of lesion • PB Rollover • Surgery candidacy • Hearing aid candidacy • If poor WRS, may not be a good candidate

  23. Word Recognition Consideration Examples

  24. Dx: Otosclerosis Tx: Stapedectomy Q: Which side?

  25. - Rollover + Rollover

  26. Very Poor WRS May not be a good hearing aid candidate Consider CROS style or additional testing

  27. Tympanometry

  28. Tympanometry • Graphic representation of ear compliance in relation to static pressure changes

  29. Normative Tympanometry Values Children Ages 3-5 years Adults Peak Pressure is typically WNL in the range of -150 to +25 daPA Compliance refers to mobility of tympanic membrane Margolis and Heller (1987)

  30. Tympanometric Configurations: Middle Ear Pathology Examples

  31. Tympanometric Configurations:Middle Ear Pathology Type A Type As • Normal or Hypomobility • Otosclerosis

  32. Tympanometric Configurations:Middle Ear Pathology • Negative pressure • Eustachian Tube dysfunction • Developing otitis media • TM retraction Type C

  33. Tympanometric Configurations:Middle Ear Pathology • Hypermobile • Aging • Atrophic scars • Healed perforation • Ossicular discontinuity Type Ad

  34. Tympanometric Configurations:Middle Ear Pathology • Flat • Perforated TM • Patent PE tube Type B ECV = 7.0

  35. Tympanometric Configurations:Middle Ear Pathology • Flat • Middle ear fluid • Serous Otitis • Blocked PE tube Type B ECV = 1.0

  36. Tympanometric Configurations:Middle Ear Pathology • Flat • Impacted cerumen Type B ECV = 0.2

  37. Tympanometric Configurations:Middle Ear Pathology • Middle ear fluid Type B? Type As?

  38. ART and AR Decay Acoustic Reflexes

  39. Acoustic Reflexes • Acoustic reflex threshold (ART): • Lowest level at which an AR can be obtained • Most sensitive to middle ear pathology • Normative Values • Present for SNHL up to 50 dB • WNL from 70 to 100 dB • Elevated responses (≥100 dB) for thresholds < 50 dB

  40. Stapedial Reflex Arc • Presentation of an intense sound elicits a contraction of the stapedius muscle • Changes the ear’s immittance

  41. “Probe Right” Acoustic Reflexes Probe Stimulus (contra) Stimulus (ipsi)

  42. Common Acoustic Reflex Patterns Examples

  43. ART Patterns:Unilateral CHL • CHL, AD • WNL, AS

  44. ART Patterns:VIII CN or CPA outside of brainstem • Mild high frequency SNHL, AD • WNL, AS

  45. ART Patterns:Lesions within brainstem which involve reflex pathways • Mild high frequency SNHL, AU

  46. ART Patterns:Facial Nerve Lesion • WNL, AU • Absent probe right • Lesion proximal to stapedius nerve • Verticle segment of facial nerve

  47. ART Patterns:Cochlear Impairment

  48. Acoustic Reflex Decay • Retrocochlear Test • Measure of ability to maintain reflex contraction during a continuous stimulation • Positive Result • Response decays to ≥ ½ its original magnitude

  49. Techniques, Age-Appropriate Results, Management Pediatric Audiometry

  50. Testing Techniques:Newborns and Infants • Otoacoustic Emissions (OAE) • Measures pre-neural signals produced by outer hair cells • Objective measure • Quick and easy • Non-invasive • Sensitive to: • Presence of hearing loss • Problems affecting integrity of cochlea • Auditory Brainstem Response (ABR) • If baby does not pass OAE

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