assessment of hearing

1. Assessment of Hearing
Dept. of ENT

2. Pure Tone Audiometry
• An audiometer is the electronic device which
produces pure tones.
• The amount of intensity that has to be raised
above the normal level is the measure of the
degree of hearing impairment.
• It is plotted in the form of graph called
AUDIOGRAM

3. • Audiometry (from the Latin audīre, "to hear", and
metria, “to measure) is a branch of Audiology,
and is the science of measuring hearing acuity
for variations in sound intensity and frequency.
• An audiometer is the device used to produce
sound of varying intensity and frequency.
Ear Phone to test
Air conduction
threshold
Response switch
Bone oscillator to test
Bone conduction
threshold

4. Air vs. Bone Conduction
• A/C (Air conduction)
– Checks the validity of entire ear system
– Tests that ipsilateral ear
B/C (Bone conduction)
– Bone vibrator is Placed on Mastoid Process
– Tests the validity of only the inner ear
– Tests better cochlea

5. procedure

6. Markings

7. Ranges of Hearing Loss

8. Normal Hearing

9. Conductive Hearing Loss

10. Sensorineural Hearing Loss

11. Mixed Hearing Loss

12. Tympanometry or impedence audiometry
• Tympanometry is an examination used to test
the condition of the middle ear and mobility of
the eardrum (tympanic membrane) and the
conduction bones by creating variations of air
pressure in the ear canal.
• In evaluating hearing loss, tympanometry
permits a distinction between sensorineural and
conductive hearing loss

13. Principles of Tympanometry
• Introduces a pure tone into ear canal
through 3-function probe tip
–Manometer (pump) varies air pressure
against TM (controls mobility)
–Speaker introduces 220Hz probe tone
–Microphone measures loudness in ear
canal

15. Principle

16. types

17. Normal tympanogram (Type A)
Peak at 0 daPa
Best movement of drum when no
extra pressure on either side of
TM

18. Other Type A tympanograms
Peak at 0daPa, but
unusually high
amplitude
Ossicular disruption
Peak at 0daPa, but
unusually low
amplitude
Stapes fixation

19. Flat tympanogram (Type B)
• When tymp is flat,
usually means 1 of 2
things:
1. Artefact
2. Fluid in ME

20. Negative tympanogram (Type C)

21. BERA or ABR or BAEP
•
Auditory brainstem response (ABR) audiometry is a
neurologic test of auditory brainstem function in response
to auditory (click) stimuli.
Brain stem evoked response audiometry,
Auditory brain stem response, ABR audiometry,
BAER (Brainstem auditory evoked response audiometry).
First described by Jewett and Williston in 1971

22. • ABR audiometry refers to an evoked potential
generated by a brief click or tone pip transmitted from
an acoustic transducer in the form of an insert earphone
or headphone. The elicited waveform response is
measured by surface electrodes typically placed at the
vertex of the scalp and ear lobes.
• The amplitude (microvoltage) of the signal is
averaged and charted against the time (millisecond),
much like an EEG.
• The waveform peaks are labeled I-VII.

27. Criteria for screening newborn babies using BERA
• 1. Parental concern about hearing levels in their child
• 2. Family history of hearing loss
• 3. Pre and post natal infections
• 4. Low birth weight babies
• 5. Hyperbilirubinemia
• 6. Cranio facial deformities
• 7. Head injury
• 8. Persistent otitis media
• 9. Exposure to ototoxic drugs

28. Uses of BERA
• 1. It is an effective screening tool for evaluating
cases of deafness due to retrocochlear
pathology i.e. (Acoustic schwannoma).
• 2. Used in screening newborns for deafness
• 3. Used for intraoperative monitoring of central and
peripheral nervous system
• 4. Monitoting patients in intensive care units
• 5. Diagnosing suspected demyelination disorders