Electrophysiological Measures of the Auditory System

1. Electrophysiological Measures of the Auditory System Perry C. Hanavan, Au.D. Audiologist

2. Electrophysiological Tests • Immittance • Evoked Potential • Otoacoustic Emissions

3. First • Observations • Appearance of person, age, gender, unusual characteristics • Patient information, case history, self-assessment, other clinical data • Otoscopic exam

4. Electrophysiologic Triage Trio • Tympanogram • Acoustic Reflex • Otoacoustic Emissions

5. Triage Trio Normal peripheral and lower brainstem function (possible APD) normal hearing Tympanogram Type A Acoustic Reflexes Normal OAE Normal Cochlear loss, outer hair cell loss, ABR normal, hearing aids beneficial Tympanogram Type A Acoustic Reflexes Normal Range Normative Data OAE Absent or Depressed Auditory Neuropathy/ Auditory Dys-synchrony Tympanogram Type A Acoustic Reflexes Absent or Elevated OAE Present Severe or profound inner ear loss (occasionally otosclerosis) Tympanogram Type A Acoustic Reflexes Absent OAE Absent Conductive or mixed loss (possible severe/profound loss) Tympanogram Not Type A Acoustic Reflexes Absent OAE Absent

6. Immittance • Ear Canal Volume (ECV or PVT) • Tympanometry • Static Compliance • Acoustic Reflex, Decay, & Latency

7. Ear Canal Volume • Measure at +200 mmH20 • Provides measure of volume of external ear canal • Volumes based on age • Volumes greater than 2.5 mmH2O (adult) or 2.0 (child) suggest: • Perforation or • Patent PE tube

8. Tympanometry • Objective measure of the function of the TM and middle ear • 5 or 6 basic shapes

9. Which type tympanogram indicates normal middle ear function? • A • B lo • C • Ad • As • Ap

10. Tympanogram Types

11. AC Type A Tympanogram A BC Normal or SN

12. AC A D Type AD Tympanogram BC Disarticulation

13. AC A S Type AS Tympanogram BC Otosclerosis

14. AC B Low Type BLow Tympanogram BC OME

15. AC B Hi Type BHi Tympanogram BC Perforation

16. AC Type C Tympanogram C BC Eustachian Tube Dysfunction

17. AC A P Type AP Tympanogram BC Acute Otitis Media

18. Static Compliance (Peak Compliance) Static Compliance – SC Ear Canal Volume – ECV Middle Ear Volume – MEV Peak Volume – PV SC = PV – ECV The ECV reflects the volume in the ear canal as the ECV measure is often made at +200 in which the TM is very stiff reflecting most of the acoustic energy (acoustic energy is not absorbed by middle ear) The PV reflects the ear canal volume AND the middle ear volume as the measure is made where the tympanogram peaks or in other words, the measure is made where the TM is most compliant or mobile; thus it is assumed that the PV represents the volume of the OE and the ME. Thus, the SC, or PV minus the ECV, represents the ME volume The normal range for our equipment ranges from .25 to 2.5 OE Ear Canal Volume (ECV) ME Volume (Static Compliance) OE and ME Volume (Peak Volume)

19. Static Immitance • The terms peak compliance (ml, cc or cm3) and peak static acoustic admittance (mmho) can be used interchangeably when using a 226Hz probe tone. • Most references use the term static admittance (SA) when reporting results. • In the most recent edition of Katz et al 2009, there is a comprehensive list of large scale studies that reported normative ranges for peak SA. • Summarizing across these studies, the 90% range for a normal tympanogram is .2 to 1.8. Shanks, J., & Shohet, J (2009). Tympanometry in clinical practice. In J. Katz, L. Medwetsky, R. Burkard, & L. Hood (Eds.), Handbook of clinical audiology (6th ed.) (pp. 157-188). Baltimore: Lippincott, Williams & Wilkins.

20. Static Compliance(Peak Compliance) Acceptable Range by Age Flaccid: disarticulation, flaccid TM, etc. 0.9 1.8 Normal mobility Stiff: otosclerosis, fluid, tympanosclerosis, etc. 0.2 0.2 Child Adult

21. Tympanometric Width Normative Cutoff Values (if larger, abnormal) Infant: 235 daPa 1 – 10 yr olds: 200 daPa Adults: 235 daPa

22. ART

23. Abnormal ART

24. Recruitment • ART – AC PT =< 60 indicates recruitment • (cochlear pathology)

25. Reflex Decay

26. Bekesy Passive Broadly tuned Studied dead cochlea Awarded Nobel Prize Gold Active Fine tuned Studied live responses Went on as an astronomer Bekesy vs. Gold

27. Otoacoustic Emissions • David Kemp disovered OAEs • Acoustic energy produced by the cochlea and recorded in the external auditory canal • Most likely energy produced by outer hair motility and possibly outer hair cell cilia • Objective test • DPOAE • TEOAE

28. DPOAE

29. DPOAE

30. Evoked Potentials • EcochG • ABR • Middle Latency • Late Response

31. OAE & ABR Screen

32. ABR Wave I Auditory Nerve II Auditory Nerve III Cochlear Nuclei IV SOC V ??? Interwave Latencies Absolute Latencies

33. ABR Supra-aural Phone Data Add .9 to Absolute values when using insert phones

34. Newborn ABR Latency Data

35. Auditory Processing • Dichotic Sentence Identification • Dichotic sentence testing is a binaural separation test procedure used to determine levels of auditory maturation, hemispheric dominance for language, and to identify disordered or damaged central auditory pathways. • The advantage of testing binaural separation with both word and sentence stimuli is to compare findings obtained with both simple and more complex linguistic levels of auditory stimuli.

36. Dichotic Sentence Identification • The DSI test uses 6 of the same sentences as the SSI-ICM test but presents 1 sentence to each ear simultaneously at 50-dB SL, and the participant is asked to select from a printed list which 2 sentences were heard. • Fifer et al showed that the test is resistant to the effects of SNHL below 50 dB HL. • The DSI test is administered in both a free and a directed mode. • In the directed mode, only the sentence heard in test ear is noted, whereas in the free mode, the sentences heard in both ears are reported. • Five presentations are used if the score is 100%; otherwise, another 5 sentences per ear are administered. • Scores are better in the directed mode than in the free mode, and the right ear scores are normally higher in adults than the left ear scores, presumably due to age related corpus callosum dysfunction. • Normal scores are 80% correct and above.

37. Pediatric Speech Intelligibility(Closed Set)(Recorded) • PSI • Both monosyllabic words and sentences recorded in quiet and with competition. • Employs color plates with pictures of animals (animals used to avoid ethnic biases) which represent either the sentences or the words. • Investigates peripheral and auditory processing disorders.

38. BKB-SIN (Adults)

39. BKB-SIN (Children)

40. Fig 8-1 ECV= .5 ECV= .6

41. Fig 8-2 ECV= .9 ECV= 1.3

42. Fig 8-3

43. Fig 8-4

44. Fig 8-5

45. Fig 8-6

46. Fig 8-7

47. Fig 8-8

48. Fig 8-12

49. Fig 8-14

50. Fig 8-15