AUDIOLOGY

1
AUDIOLOGY

• Danielle Billing

2
The Hearing Mechanism

• Outer Ear
• The part of the ear that is visible, often called
  the Pinna, and the ear canal, also called the
  External Auditory Meatus

• Inner Ear
• The cochlea

Middle Ear Consists of the tympanic membrane
(eardrum) and the ossicles (bones)
Auditory Nerve The nerve responsible for
sending/ receiving auditory information
Peripheral Mechanism
3
The Hearing Mechanism

• The Brain
• Responsible for processing and interpreting
  auditory information

Central Mechanism
4
The Hearing Mechanism

• Outer Ear

• Inner Ear

Middle Ear
Auditory Nerve
5
The Hearing Mechanism

• The Brain

6
The Hearing Mechanism

• Outer Ear
• Acoustic Energy

• Inner Ear
• Hydraulic Energy

Middle Ear Mechanical Energy
Auditory Nerve Electrical Energy
?
?
?
7
Common Causes of Hearing Loss

• Outer Ear
• Otitis Externa
• Microtia
• Anotia

• Inner Ear
• Meningitis
• Noise damage
• Heredity

Middle Ear Otitis Media Allergies Cholesteotoma
Eustachian tube disfunction Mastoiditis Otoscl
erosis
Auditory Nerve Auditory Neuropathy
Peripheral Mechanism Conductive Loss
Central Mechanism Sensorineural Loss
?Mixed Loss?
8
Types of Hearing Loss

• Conductive Loss
• A hearing loss caused by an obstruction or
  dysfunction of the outer or middle ear

• Sensorineural Loss
• A hearing loss caused by a dysfunction in the
  inner ear (sensori), or the central processing
  system (neural)

• Mixed Loss
• A hearing loss caused by a combination of
  Conductive and Sensorineural Losses

9
Degrees of Hearing Loss

• Normal 10 or better
• Minimal 11-25 d
• Mild 26-40
• Moderate 41-55
• Moderately severe 56-70
• Severe 71-90
• Profound greater than 90

10
Behavioral testing

• Requires the patient to respond to a stimulus

11
Introduction to Audiograms What is an audiogram?

• An audiogram is a graphical representation of the
  hearing thresholds of an individual
• These thresholds are determined by the
  individuals response to tones presented via
  earphones or ear inserts (air conduction), or a
  bone oscillator (bone conduction)

12
Introduction to Audiograms the Decibel

• Decibel levels of common sounds
• 0 dB- The softest sound a person can hear with
  normal hearing
• 10 dB- normal breathing
• 20 dB- whispering at 5 feet
• 30 dB- soft whisper
• 50 dB- rainfall
• 60 dB- normal conversation
• 110 dB- shouting in ear
• 120 dB- thunder

13
Audiograms and Type of Loss
14
Speech testing

• Two basic types
• Speech threshold tests
• Speech recognition (supra-threshold) tests

15
Speech Threshold Testing

• Lowest level at which speech can be recognized or
  detected
• SRT- speech recognition threshold
• ST- spondee threshold
• A spondee is a two-syllable word with each
  syllable receiving equal emphasis
• The patient must correctly identify the speech
  material presented, typically by repeating the
  word
• The SRT and pure tone average should be within
  /- 10 dB of each other

16
Supra-threshold Speech TestingSpeech
Recognition Ability (SRA)

• Ability to correctly recognize speech at
  supra-threshold levels (reported in percentage of
  correct responses at the intensity level of
  presentation)
• 100 at 70 dB HL
• 92 at 50 dB SL

17
Electroacoustic and Electrophysiological testing

• Does not require the patient to respond
  responses are unconscious and automatic

18
Ear Canal Volume (ECV)

• Provides measure of volume of external ear canal
• Volumes greater than 2.5 suggest
• Perforation or
• Patent PE tube

19
Tympanometry

• Purpose to test the function of the tympanic
  membrane and middle ear
• Method air is added and subtracted from the EAM
  while a tone is presented
• Results presented on a graph called a tympanogram

20
Tympanometry Interpreting results

• The shape of the tympanogram indicates the
  functionality of the middle ear

21
Tympanometry Interpreting results
Type A
Type Ad
Type As
Flaccid tympanic membrane Ossicular
disarticulation (broken ossicular chain)
Normal Middle Ear
Stiff tympanic membrane Otosclerosis Tympanosclero
sis
22
Tympanometry Interpreting results
Type B (low)
Type B (high)
Type C
Non-patent PE tubes
Patent PE tubes
Negative middle ear pressure
23
Static Immitance

• Definition the height of the tympanogram at its
  peak
• Helpful in diagnosing middle ear dysfunction
• Able to detect small perforations in the tympanic
  membrane

24
Static Immittance Interpreting results
Flaccid disarticulation, flaccid TM, etc.
2.5
Normal
.25
Stiff otosclerosis tympanosclerosis, etc.
25
Acoustic Reflex Threshold (ART)

• When a sound is of sufficient intensity, it will
  elicit a reflex of the middle ear musculature
  (Stach, 1998, p.270)
• The ART measures the threshold a which this
  reflex of the stapedius muscle occurs
• Two types of reflex
• Ipsilateral-reflex of the muscle of the
  stimulated ear- uncrossed
• Contralateral-reflex of the muscle of the
  non-stimulated ear- crossed

26
Acoustic Reflex Threshold (ART) Interpreting
results

• Individuals with normal hearing will have an ART
  between 70 and 100 dB HL
• An elevated or absent response indicates a
  pathology of the hearing mechanism

27
Acoustic Reflex Threshold (ART) Interpreting
results

• An absent contralateral reflex could indicate
  (when stimulus is presented to the right ear)
• Right middle ear disorder
• Right severe sensorineural loss
• Right acoustic tumor
• Brainstem lesion
• Left facial nerve disorder
• Left middle ear disorder

28
Auditory Brainstem Response (ABR)

• Measures brainstem response to a auditory
  stimulus
• Wave pattern consisting of 5 positive peaks
  distance between peaks indicates the amount of
  time between stimulus and response

29
Otoacoustic Emissions (OAE)

• Measure of the function of the outer hair cells
  (OHC) of the cochlea
• Useful for
• Infant screening
• Pediatric assessment
• Monitoring cochlear function

30
Put it all together

• By using a combination of behavioral,
  electroacoustic, and electrophysiological testing
  through individual analysis and crosschecking, a
  proper diagnosis and treatment of audiological
  disorders can occur

31
The End

• or is it?