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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

Auditory Assessment

Bastaninejad, Shahin, MD, ORL-HNS

Assistant Prof., TUMS

Amiralam Hospital

Acknowledgment: I would like to appreciate Prof. Borghei, for preparing this presentation


Auditory assessment

CHL

SNHL


Auditory assessment1
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)

    • ...


Tuning fork tests tft
Tuning Fork Tests (TFT)

  • Rinne’s test

  • Weber’s test

  • Absolute Bone Conduction (ABC)


Auditory assessment

Rinne’s Test


Tuning fork tests tft1
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



Tuning fork tests tft2
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


Tuning fork tests tft3
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


Pure tone audiometry pta
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



Pure tone audiometry pta2
Pure Tone Audiometry (PTA)

Normal Audiogram


Pure tone audiometry pta3
Pure Tone Audiometry (PTA)

Range of hearing loss


Pure tone audiometry pta4
Pure Tone Audiometry (PTA)

Conductive Hearing Loss (CHL)


Pure tone audiometry pta5
Pure Tone Audiometry (PTA)

Sensori-Neural Hearing Loss (SNHL)


Pure tone audiometry pta6
Pure Tone Audiometry (PTA)

Mixed Hearing loss


Masking
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


Speech audiometry
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


Auditory assessment

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)


Speech audiometry1
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


Impedance audiometry
Impedance Audiometry

  • Objective test

  • Includes :

    • Tympanometry

    • Acoustic Reflex

    • External Canal Volume (ECV)


Tympanometry
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


Tympanometry1
Tympanometry

Peak between -100 to +100


Tympanometry2
Tympanometry

Peak usually in-150 to -200


Tympanometry3
Tympanometry

Peak is under -300



Acoustic reflex
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


Acoustic reflex1
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


Auditory assessment
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


Auditory assessment

Middle and Long Latency Response (MLR,LLR)

Lateral lemniscus

5th

Cochlear nucleus

ABR

3rd

4th

Sup. Olivary Complex

1st and 2nd



Oto acoustic emission oae
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