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Auditory Assessment

Auditory Assessment. Bastaninejad , Shahin , MD, ORL-HNS Assistant Prof., TUMS Amiralam Hospital Acknowledgment: I would like to appreciate Prof. Borghei , for preparing this presentation. CHL. SNHL. Auditory Assessment. Subjective tests Tuning fork tests (TFT)

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Auditory Assessment

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  1. Auditory Assessment Bastaninejad, Shahin, MD, ORL-HNS Assistant Prof., TUMS Amiralam Hospital Acknowledgment: I would like to appreciate Prof. Borghei, for preparing this presentation

  2. CHL SNHL

  3. Auditory Assessment • Subjective tests • Tuning fork tests (TFT) • Pure tone audiometry (PTA) • Speech audiometry • Objective tests • Impedance audiometry (Tym,AR) • Auditory Brainstem Response (ABR) • Otoacoustic Emission (OAE) • ...

  4. Tuning Fork Tests (TFT) • Rinne’s test • Weber’s test • Absolute Bone Conduction (ABC)

  5. Rinne’s Test

  6. Tuning Fork Tests (TFT) Rinne’s Test • Principal: AC>BC • Rinne+: AC>BC, normal hearing or sensorineural hearing loss • Rinne-: AC<BC, conductive HL • False Rinne–: unilateral deep SNHL, due to cross over phenomena ,this can be avoided with masking

  7. Weber’s Test

  8. Tuning Fork Tests (TFT) Weber’s Test • Principal: compares the BC of the two ears • Normal: hears equal on both sides or does not hear at all • Conductive HL: lateralized to the more affected side • SNHL: lateralized to the less affected side

  9. Tuning Fork Tests (TFT) Absolute Bone Conduction test (Schwabach test) • Compares the BC of the examiner with the patient • Normal: equal to the examiner • CHL: longer than the examiner • SNHL: less than the examiner

  10. Pure Tone Audiometry (PTA) • It is the graphic record of hearing Quantitatively & Qualitatively • Pure tones are delivered by head-phone for AC & by a vibrator for BC • X-Axis: Frequency range 125 – 12000 Htz(routinely depicted from 250-8000 Htz) • Y-Axis: Intensity of sound in decibels (dB) • A decibel is the smallest change in the intensity of sound which can be recognized by normal human ear

  11. Pure Tone Audiometry (PTA)

  12. Pure Tone Audiometry (PTA) Normal Audiogram

  13. Pure Tone Audiometry (PTA) Range of hearing loss

  14. Pure Tone Audiometry (PTA) Conductive Hearing Loss (CHL)

  15. Pure Tone Audiometry (PTA) Sensori-Neural Hearing Loss (SNHL)

  16. Pure Tone Audiometry (PTA) Mixed Hearing loss

  17. Masking • To prevent ‘crossover’ phenomena • Crossover happens with • 40-60 dB AC difference in two ears • 0-20 dB BC difference in two ears • Masking problem • Masking dilemma; in bilateral CHL or Bilateral Mixed HL • Overmasking masking noise crosses over to the other side

  18. Speech Audiometry • Recorded voice is used Speech Detection threshold(SDT) • An intensity level at which a listener can barely discern the presence of a speech signal in 50% of the time • It is equal to the PTA average obtained at 500,1000,2000Hz

  19. Speech Reception Threshold (SRT) Two syllabus words (Spondee) With different intensities The intensity at which 50% of the presented words can be repeated Measured in dB (it is usually 8-9dB more than SDT)

  20. Speech Audiometry Speech Discrimination Score (SDS) • Mono syllable words • At 50dB higher than SRT • Percentage of words recognized correctly is noted • Normal: 96-100% • CHL: 90-100% • SNHL: low • Retro cochlear: very low

  21. Impedance Audiometry • Objective test • Includes : • Tympanometry • Acoustic Reflex • External Canal Volume (ECV)

  22. Tympanometry • Record of resistance of conductive mechanism of ear against pressure changes of external canal • Type A:normal • Type B:OME, TM perforation, unfit probe, middle ear mass • Type C: Eustachian tube dysfunction • Type As: otosclerosis, tympanosclerosis • Type Ad:ossicular dislocation, or Atrophic TM • Type D: Scarred TM, or normal hypermobile TM

  23. Tympanometry Peak between -100 to +100

  24. Tympanometry Peak usually in-150 to -200

  25. Tympanometry Peak is under -300

  26. Tympanometry

  27. Acoustic Reflex • Stapedial muscle contraction in response to loud noise • 70-100 dB above hearing threshold • Particularly useful for DDx between Cochlear and Retrocochlear lesions • Afferent : cochlear (8th) nerve • Efferent : facial (7th)nerve

  28. Acoustic Reflex Absent bilaterally when tested ear has CHL BC must be better than 60dB to elicit this reflex AR negative in tested ear but + in the contralateral Retrocochlear lesion AR Positive in Ipsi., but negative in Contra. Brain Stem lesion It also demonstrate level of facial nerve lesion

  29. ABR • Surface recording of the electrical activity of auditory pathway in response to sound  Sensitive for Retro-cochlear lesion • Wave 1 & 2: cochlear nerve • Wave 3: cochlear nucleus complex • Wave 4: Superior olivery complex • Wave 5: lateral leminiscus

  30. Middle and Long Latency Response (MLR,LLR) Lateral lemniscus 5th Cochlear nucleus ABR 3rd 4th Sup. Olivary Complex 1st and 2nd

  31. ABR

  32. Oto-Acoustic Emission (OAE) • Normal cochlea generate a sound Due to the biological activity of outer hair cells • They are of 2 types: • Spontaneous emission (Spont.OAE50-70% of people) • Evoked otoacoustic emission

  33. Any Question!?

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