Auditory function-slides-2004-0211 2

1. Assessment of Peripheral Assessment of Peripheral
and Central Auditory and Central Auditory
FunctionFunction
February 11, 2004February 11, 2004
Steven T. Wright, M.D.Steven T. Wright, M.D.
Arun K. Gadre, M.D.Arun K. Gadre, M.D.

2. 2
Auditory FunctionAuditory Function
Complex auditory pathwayComplex auditory pathway
Peripheral Auditory AssessmentPeripheral Auditory Assessment
Basic armament of the otolaryngologistBasic armament of the otolaryngologist
Central Auditory AssessmentCentral Auditory Assessment
Relatively new interestRelatively new interest
MultidisciplinaryMultidisciplinary

3. 3
Ossicular AmplificationOssicular Amplification

4. 4
AnatomyAnatomy

5. 5
Tonotopic organizationTonotopic organization

6. 6
AnatomyAnatomy

7. 7
Peripheral Auditory AssessmentPeripheral Auditory Assessment
Pure Tone AudiometryPure Tone Audiometry
Speech AudiometrySpeech Audiometry
Acoustic ImmittanceAcoustic Immittance
Auditory Brainstem ResponsesAuditory Brainstem Responses
ElectrocochleographyElectrocochleography
Otoacoustic EmissionsOtoacoustic Emissions

8. 8
Pure Tone AudiometryPure Tone Audiometry
Most common Most common
Pure tones (sinusoids) are tonotopically Pure tones (sinusoids) are tonotopically
maintained by the cochlea.maintained by the cochlea.
Air conduction testingAir conduction testing
Octave frequenciesOctave frequencies
Interoctave frequenciesInteroctave frequencies
Bone conduction testingBone conduction testing

9. 9
Pure tone audiometryPure tone audiometry

10. 10
Decibel ScaleDecibel Scale
Audiologic unitsAudiologic units
dB SPL: sound pressure leveldB SPL: sound pressure level
dB HL: hearing leveldB HL: hearing level
dB SL: sensation leveldB SL: sensation level
Audiometric 0Audiometric 0
dB= 10 log 10dB= 10 log 10

11. 11
Frequency SensitivityFrequency Sensitivity
Human hearing spectrum from 20- 20,000Hz.Human hearing spectrum from 20- 20,000Hz.
Differentially sensitiveDifferentially sensitive
125Hz : 45dB125Hz : 45dB
1000Hz: 6.5dB1000Hz: 6.5dB
10,000Hz: 20dB10,000Hz: 20dB

12. 12
Audiogram LevelsAudiogram Levels
NormalNormal
0 - 20dB 0 - 20dB
MildMild
20 - 40dB20 - 40dB
ModerateModerate
40 – 60dB40 – 60dB
SevereSevere
> 60 dB> 60 dB

13. 13
Audiogram- Speech BananaAudiogram- Speech Banana

14. 14
CrossoverCrossover
Audiometric results are only valid when the Audiometric results are only valid when the
results are actually of the test ear.results are actually of the test ear.
Interaural attenuation reflects crossover.Interaural attenuation reflects crossover.
Air conduction from 40-80dBAir conduction from 40-80dB
Bone conduction even at 0dBBone conduction even at 0dB

15. 15
MaskingMasking
The audiometric technique used to eliminate The audiometric technique used to eliminate
responses by the non-test ear.responses by the non-test ear.
An appropriate noise is presented to the non-An appropriate noise is presented to the non-
test ear while the test ear is being tested.test ear while the test ear is being tested.
Masking level must exceed the non-test ear Masking level must exceed the non-test ear
threshold, but not create crossover.threshold, but not create crossover.

16. 16
Speech AudiometrySpeech Audiometry
Determines how well a person hears and Determines how well a person hears and
understands speech.understands speech.
Spondee wordsSpondee words
SRTSRT
SRT should be in close correlation with PTA.SRT should be in close correlation with PTA.

17. 17
Speech AudiometrySpeech Audiometry
Word recognition scoring %Word recognition scoring %
20-50 Phonetically balanced words20-50 Phonetically balanced words
Conductive hearing lossConductive hearing loss
Excellent WRSExcellent WRS
Sensorineural hearing lossSensorineural hearing loss
Poor WRSPoor WRS
RolloverRollover

18. 18
RolloverRollover
Code intensity of neural discharges usually Code intensity of neural discharges usually
occurs by 3 mechanisms:occurs by 3 mechanisms:
Pure monotonicPure monotonic
- - - - - - - - - --------------- - - - - - - - - --------------
Monotonic at low intensityMonotonic at low intensity
- - - - - - - - - - - - - - -- - - - - - - - - - - - - - -
Monotonic with reversal at increasing frequencyMonotonic with reversal at increasing frequency
- - - - - - - - - - -- - - - - - - - - - -

19. 19
Auditory behavior index for infantsAuditory behavior index for infants

20. 20
Acoustic ImmittanceAcoustic Immittance
Impedance: resistance to acoustic flowImpedance: resistance to acoustic flow
Admittance: ease of acoustic flowAdmittance: ease of acoustic flow
Tested by:Tested by:
TympanometryTympanometry
Acoustic Stapedial ReflexAcoustic Stapedial Reflex

21. 21
TympanometryTympanometry
by Jergerby Jerger

22. 22
Stiffness vs. MassStiffness vs. Mass

23. 23
Acoustic Stapedial ReflexAcoustic Stapedial Reflex
Lowest intensity required to elicit a stapedial Lowest intensity required to elicit a stapedial
muscle contraction.muscle contraction.
3 primary acoustic reflex characteristics3 primary acoustic reflex characteristics
Presence or absence of the reflexPresence or absence of the reflex
Reflex thresholdReflex threshold
Reflex DecayReflex Decay

24. 24
Acoustic Reflex DecayAcoustic Reflex Decay
Measures the ability of the stapedius muscle to Measures the ability of the stapedius muscle to
maintain sustained contraction.maintain sustained contraction.
Lower frequency tone/noise for 10 secondsLower frequency tone/noise for 10 seconds

25. 25
Acoustic Reflex in Cochlear Acoustic Reflex in Cochlear
DisordersDisorders
Primarily determined by the degree of hearing Primarily determined by the degree of hearing
loss.loss.
Less than 50dB: normalLess than 50dB: normal
Between 50-80dB: proportionally elevatedBetween 50-80dB: proportionally elevated
Greater than 50dB: absentGreater than 50dB: absent

26. 26
Acoustic ReflexAcoustic Reflex
Tone vs. NoiseTone vs. Noise
Broadband Noise usually has 20-25dB lower Broadband Noise usually has 20-25dB lower
thresholds than the reflex thresholds for tones.thresholds than the reflex thresholds for tones.
Physiologically not possible to have behavioral Physiologically not possible to have behavioral
thresholds higher than acoustic reflex thresholds thresholds higher than acoustic reflex thresholds
for tones. (malingerers)for tones. (malingerers)

27. 27
Facial ParalysisFacial Paralysis
Absent or abnormal stapedial reflex when the Absent or abnormal stapedial reflex when the
recording probe is ipsilateral to the side of the recording probe is ipsilateral to the side of the
lesion.lesion.
Can also be helpful in locating lesions proximal Can also be helpful in locating lesions proximal
or distal to the stapedial muscle.or distal to the stapedial muscle.

28. 28
Eighth nerve lesionsEighth nerve lesions
Absent reflexes when stimuli is presented to the Absent reflexes when stimuli is presented to the
affected ear.affected ear.
Reflexes in eighth nerve lesions are not Reflexes in eighth nerve lesions are not
dependent on the degree of hearing loss.dependent on the degree of hearing loss.
Rapid reflex decayRapid reflex decay

29. 29
Auditory Brainstem ResponsesAuditory Brainstem Responses
Impulses that are generated by the auditory Impulses that are generated by the auditory
neural pathway that can be recorded on the neural pathway that can be recorded on the
scalp.scalp.
Not a direct measure of hearing.Not a direct measure of hearing.
Detected as early as 25wks gestation.Detected as early as 25wks gestation.
Not affected by sleep, sedation, or attention.Not affected by sleep, sedation, or attention.

30. 30
Click or Transient EvokedClick or Transient Evoked
ABRABR
Most widely usedMost widely used
Moderate intensity levels with resultant firing of Moderate intensity levels with resultant firing of
a wide range of neural frequency units.a wide range of neural frequency units.
Repeatable Wave V to within 10dB of Repeatable Wave V to within 10dB of
behavioral responses.behavioral responses.
Limited by frequency specificityLimited by frequency specificity

31. 31
Tone Burst ABRTone Burst ABR
More accurate results than click-evoked ABRMore accurate results than click-evoked ABR
Increased latency periods than click-evoked.Increased latency periods than click-evoked.

32. 32
Bone Conduction ABRBone Conduction ABR
As reliable and repeatable as air conduction As reliable and repeatable as air conduction
ABR.ABR.
Particularly useful in structural abnormalitiesParticularly useful in structural abnormalities
Canal Atresia or stenosisCanal Atresia or stenosis

33. 33
ABRABR
Primary goal is a clear and reliable Wave IPrimary goal is a clear and reliable Wave I
Wave I : distal 8Wave I : distal 8
thth
nerve nerve
Wave II : proximal 8Wave II : proximal 8
thth
nerve nerve
Wave III : cochlear nucleiWave III : cochlear nuclei
Wave IV : SOCWave IV : SOC
Wave V : Lateral LemniscusWave V : Lateral Lemniscus

34. 34
ABRABR

35. 35
ABRABR
Infant vs AdultInfant vs Adult
Less waveform morphologyLess waveform morphology
Increased absolute and interwave latenciesIncreased absolute and interwave latencies
Should correct by 18-24 months of age.Should correct by 18-24 months of age.

36. 36
ElectrocochleographyElectrocochleography
EcoGEcoG
Measures stimulus related potentials of the most Measures stimulus related potentials of the most
peripheral portions of the auditory system.peripheral portions of the auditory system.
3 major components:3 major components:
Cochlear microphonicCochlear microphonic
Summating potentialSummating potential
Action potentialAction potential

37. 37
EcoGEcoG
Electrode placementElectrode placement
NoninvasiveNoninvasive
Ear canalEar canal
>50%>50%
Tympanic membraneTympanic membrane
>40%>40%
InvasiveInvasive
TranstympanicTranstympanic
>30%>30%

38. 38
EcoGEcoG
Meniere’s diseaseMeniere’s disease

39. 39
Otoacoustic EmissionsOtoacoustic Emissions
Low energy sounds produced by the cochlear Low energy sounds produced by the cochlear
outer hair cells.outer hair cells.
Cochlear amplification.Cochlear amplification.
Spontaneous emissionsSpontaneous emissions
Not present in greater than 25dB hearing loss.Not present in greater than 25dB hearing loss.
Evoked EmissionsEvoked Emissions
Transient evokedTransient evoked
Distorted ProductDistorted Product

40. 40
TEOAETEOAE
Transient stimuli, clicks, evoke emissions from a Transient stimuli, clicks, evoke emissions from a
large portion of the cochlea.large portion of the cochlea.
Generally present when hearing thresholds are Generally present when hearing thresholds are
below 35dB.below 35dB.
AdvantagesAdvantages
Reliable separate normal from abnormal at 20-30dBReliable separate normal from abnormal at 20-30dB
FastFast
DisadvantagesDisadvantages
Poor at higher frequenciesPoor at higher frequencies

41. 41
DPOAEDPOAE
DP are additional tones that are created when DP are additional tones that are created when
two tones are presented. f1 and f2two tones are presented. f1 and f2
DP occurs at 2(f1-f2) by a nonlinear process.DP occurs at 2(f1-f2) by a nonlinear process.
Generally present when hearing thresholds are Generally present when hearing thresholds are
below 50dB.below 50dB.
Advantage is higher frequency (6000Hz)Advantage is higher frequency (6000Hz)

42. 42
OAEOAE

43. 43
OAE and middle ear pathologyOAE and middle ear pathology
Transmission properties of the middle ear Transmission properties of the middle ear
directly influence the OAE characteristics.directly influence the OAE characteristics.
Otitis mediaOtitis media
NewbornsNewborns
Tympanic membrane perforationsTympanic membrane perforations

44. 44
Central Auditory ProcessingCentral Auditory Processing
No accepted definition of CAP.No accepted definition of CAP.
Task Force on CAP consensus and developmentTask Force on CAP consensus and development
Sound localizationSound localization
Auditory discriminationAuditory discrimination
Auditory pattern recognitionAuditory pattern recognition
Temporal aspects of auditionTemporal aspects of audition
Auditory performance decrements with competing Auditory performance decrements with competing
and degraded acoustic signals.and degraded acoustic signals.

45. 45
CAPD CategoriesCAPD Categories
DecodingDecoding
Tolerance Fading MemoryTolerance Fading Memory
IntegrationIntegration
OrganizationOrganization

46. 46
Buffalo ModelBuffalo Model
Takes into account the classification of CAPD Takes into account the classification of CAPD
as well as speech and language evaluation and as well as speech and language evaluation and
academic characteristics.academic characteristics.
CAP batteryCAP battery
Staggered Spondaic Word (SSW) testStaggered Spondaic Word (SSW) test
Phonemic Synthesis (PS) testPhonemic Synthesis (PS) test
Speech-in-Noise (SN) testSpeech-in-Noise (SN) test
Masking Level Difference (MLD) testMasking Level Difference (MLD) test

47. 47
Decoding CategoryDecoding Category
Most common (50%)Most common (50%)
Breakdown of auditory processing at the Breakdown of auditory processing at the
phonemic level.phonemic level.
Difficulty reading and speaking & Articulation Difficulty reading and speaking & Articulation
Errors “r” & “l”Errors “r” & “l”
Posterior temporal lobePosterior temporal lobe

48. 48
Decoding categoryDecoding category
Management strategies center on improving Management strategies center on improving
phonemic and metaphonemical skills.phonemic and metaphonemical skills.
Hooked on Phonics and Phonemic Synthesis Skills Hooked on Phonics and Phonemic Synthesis Skills
programprogram
Clear and concise instructionsClear and concise instructions
Outlining objectivesOutlining objectives
Written instructionsWritten instructions

49. 49
Tolerance-fading memory categoryTolerance-fading memory category
Second most common (20%)Second most common (20%)
Poor auditory memory and difficulty understanding Poor auditory memory and difficulty understanding
speech in adverse conditions.speech in adverse conditions.
Deficits in expressive language and writing.Deficits in expressive language and writing.
Impulsive responders, short attention spans.Impulsive responders, short attention spans.
Auditory continuous performance test can screen for Auditory continuous performance test can screen for
ADHD.ADHD.
Linked to Broca’s area of the inferior frontal lobe.Linked to Broca’s area of the inferior frontal lobe.

50. 50
Tolerance-fading memoryTolerance-fading memory
Management focuses on improving the signal to Management focuses on improving the signal to
noise ratio and strengthening short term noise ratio and strengthening short term
memory skills.memory skills.
FM system is beneficial.FM system is beneficial.
Noise desensitization.Noise desensitization.
Earplugs and quiet study areas.Earplugs and quiet study areas.

51. 51
Integration categoryIntegration category
Difficulty integrating auditory information with Difficulty integrating auditory information with
visual and nonverbal aspects of speech.visual and nonverbal aspects of speech.
Deficits of the corpus callosum and angular Deficits of the corpus callosum and angular
gyrus.gyrus.
Dyslexics and poor readerDyslexics and poor reader
ManagementManagement
Improving signal to noise ratioImproving signal to noise ratio
Structured phonetically based reading exercisesStructured phonetically based reading exercises

52. 52
Organizational categoryOrganizational category
Least common category.Least common category.
Characterized by reversals and sequencing Characterized by reversals and sequencing
errors.errors.
Individuals are often disorganized at school and Individuals are often disorganized at school and
at home.at home.
ManagementManagement
Improving sequencing skills and organizational Improving sequencing skills and organizational
habits.habits.
Consistent routines, checklists, calendars.Consistent routines, checklists, calendars.

53. 53
CAPDCAPD
Multidisciplinary approachMultidisciplinary approach
OtologistOtologist
Speech PathologistSpeech Pathologist
AudiologistAudiologist
SchoolsSchools

54. 54
ConclusionConclusion
Peripheral AssessmentPeripheral Assessment
Measures of objective hearingMeasures of objective hearing
Measures of physiologic hearingMeasures of physiologic hearing
Central AssessmentCentral Assessment

55. 55
Bibliography
Ge X, Shea J. Transtympanic electrocochleography: a 10 year experience. Ge X, Shea J. Transtympanic electrocochleography: a 10 year experience.
Otology and Neurotology. 2002 Sept; 23(5): 799-805.Otology and Neurotology. 2002 Sept; 23(5): 799-805.
Hall J, Antonelli P. Assessment of the peripheral and central auditory Hall J, Antonelli P. Assessment of the peripheral and central auditory
function. In: Bailey BJ, et al, eds. Head & Neck surgery- Otolaryngology. function. In: Bailey BJ, et al, eds. Head & Neck surgery- Otolaryngology.
Philadelphia: Lippincott, 2001; 1659-1672.Philadelphia: Lippincott, 2001; 1659-1672.
Katz J, Stecker N, Henderson D, (Eds). Katz J, Stecker N, Henderson D, (Eds). Central auditory processing: A Central auditory processing: A
transdiscliplinary view. St. Louis: Mosby. 1992.transdiscliplinary view. St. Louis: Mosby. 1992.
Katz J, Masters M, Stecker N. Katz J, Masters M, Stecker N. Central auditory processing disorders: Mostly Central auditory processing disorders: Mostly
management. Needham Heights: Allyn & Bacon. 1998.management. Needham Heights: Allyn & Bacon. 1998.
Rovinett M, Glattke T. Otoacoustic emissions; Clinical Applications. New Rovinett M, Glattke T. Otoacoustic emissions; Clinical Applications. New
York: Theime. 1997.York: Theime. 1997.
Willeford J, Burleigh J. Handbook of central auditory processing disorders in Willeford J, Burleigh J. Handbook of central auditory processing disorders in
children. Orlando: Grune & Stratton. 1985.children. Orlando: Grune & Stratton. 1985.
Wiley T, Fowler C. Acoustic Immittance measures in clinical audiology. San Wiley T, Fowler C. Acoustic Immittance measures in clinical audiology. San
Diego: Singular Publishing Group. 1997.Diego: Singular Publishing Group. 1997.