Physiological Testing …
- Does not require a voluntary response from the patient
- Can help pinpoint the sit of dysfunction (“site of lesion”)
- Used as cross checkers
- particularly useful for infants and those with disabilities
Otoscopy
- This is not a physiological test
- visual inspection to verify that the ear canal is not occluded, no tubes, drainage, trauma, infection, etc.
What are the three main types of Physiological Tests?
- Immittance
- Otoacoustic Emission
- Auditory Evoked Potentials
Name the two parts of Immittance Testing:
- Tympanogram
- Acoustic Reflexes
What does Immittance Testing measure and in what units is it measured in?
- It measures acoustic immittance vs impedance
- immittance units in cm3 or mmho
- daPa/decapascals units of ear canal pressure
what are the 4 primary components of immittance testing?
- transducer
- air pump
- manometer
- microphone
Tympanometry … main points
- the first part of immittance testing
- measures the flexibility of the eardrum and how sound bounces back toward microphone as pressure changes (daPa)
- used to diagnose middle ear pathologies
A tympanogram creates _____________ with a ______ and mechanically changes the air pressure in the ear canal (_______________). It also creates a tone of ______ Hz
- an airtight seal with a probe tip
- (+200 to -400 daPa compared to atmosphere)
- 226 Hz
In infants younger than 12 months of age, we use _______ Hz tone due to the __________________.
- 1000 Hz
- smaller diameter of the ear drum
Peak immittance is at the point of _____________________.
Maximum Displacement
Zero on a tympanogram =
normal
inner and outer pressure are equal
other info on Tympanograms:
- it is rare to see a positive
- scar tissue can lead to abnormal readings due to lack of flexibility
- A = normal
- lower than A is deep
- Above A is stiff
If pressure behind the eardrum is very _______ then there is an issue with the Eustachian tube. If it is ______ then there is no movement.
- negative
- flat
Tympanogram reading of A=
peak compliance between +100 and -100 daPa
Tympanogram reading of As=
peak compliance normal but very shallow (less than 0.3 mmho)
Tympanogram reading of Ad=
peak compliance normal but very deep (grater than 1.4 mmho)
Tympanogram reading of C=
peak compliance is negative pressure (beyond -100 daPa to -400 daPa)
Tympanogram reading of B=
Flat tracing with no peak (malfunction, fluid, perforation or tube)
Ear canal volume
Normative values for ear canal sizes …
- less than 0.3 the tip may be against the canal wall
- greater than 0.2 may be measuring beyond the ear canal
- 0.4-1.0 normal for kids less than 7 yrs
- 0.6-1.5 average size for adults
Acoustic Reflex testing …
-Needs a normal tympanogram
(tubes or fluid=CNT)
-measure of the acoustic arc including afferent and efferent systems
-used to diagnose retrocochlear pathologies, can suggest pathologies of the VIII nerve or brainstem
-can be measured ipsilateral (afferent) or contralateral (efferent)
-occurs at the peak pressure of the eardrum
-test at 500, 1k, 2k 3k and 4k
-helps predict levels of hearing loss
-modern tech can self determine responses
Acoustic reflex decay testing
- tone continues for ten seconds
- if reflex decays by %50 or more it is abnormal
- often used when suspecting a vestibular schwannoma
Otoacoustic Emissions (OAE) …
- a test of cochlear function
- can be spontaneous or evoked
- low level sounds create a cochlear response that can be recorded in the ear canal
- separates cochlear from retrocochlear pathologies
- separates sensory from neural
- requires a normal conductive system (outer/middle ear)
Otoacoustic Emissions were discovered by _________ in _______ and was clinically available by the __________.
- David Kemp
- 1978
- early 90’s
What are the three kinds of evoked emissions that are used for testing?
- Transient Evoked (TEOAE)
- Distortion Product (DPOAE)
- Stimulus Frequency (SFOAE)
