Transcript hearing assessment

INTRODUCTION TO
AUDIOLOGY (SPHS 1100)
WEEK 5 POWER POINT
TOPICS
HEARING ASSESSMENT
Screening
Testing
TYPES OF TESTS USED TO EVALUATE HEARING
 Pure-Tone Audiometry
 Speech Audiometry
 Tests of Middle Ear
 Auditory Brainstem Response (ABR)
 Otoacoustic Emissions (OAEs)
GOALS and OBJECTIVES
GOAL
Learner will differentiate the different assessment
procedures to identify the hearing loss.
OBJECTIVES
 TLW list the procedures used for infant hearing
screening. (Cognitive)
 TLW conduct the different hearing tests to identify
hearing loss. (psychomotor).
 TLW diagnose the type of hearing loss based on the
hearing test results. (affective)
HEARING ASSESSMENT
Assessment includes hearing screening and testing.
Hearing Screening
 Infant screening is very important because if the
hearing loss is detected late, language development
is delayed, which affects child’s ability to learn and
perform in school.
 The Individuals with Disabilities Education Act
(IDEA) requires that infants and toddlers with
disabilities be identified and provided appropriate
screening.
HEARING ASSESSMENT
Some of the hearing screening procedures are
Behavioral Observational Screening
 It implies the observation of overt changes in behavior
that occur in response to high-intensity stimuli
presented with a handheld instrument positioned near
the infant. The behavioral responses are
 Arousal from sleep
 Startle response
 Eyeblink
HEARING ASSESSMENT
HEARING ASSESSMENT
Limitations
 The protocols must use stimuli that, at best, only
identify infants with bilateral severe or profound
hearing loss
 Determination of whether the observed change in
behavior was indeed a response to the auditory
stimulus relies on subjective judgement of observers
 State of the infant has a substantial effect on
responsiveness
HEARING ASSESSMENT
Crib O-Gram
 Crib-O-Gram device involves placement of a motionsensitive transducer under a crib mattress to detect motor
activity produced by the infant.
 The infant’s activity level is monitored automatically for 10
to 15 seconds before and 2 to 5 seconds after the
presentation of an auditory stimulus.
 The stimulus is a 2000-to 4000-HZ bandpass noise of 92
decibels sound pressure level (dBSPL) delivered from an
earphone placed in the crib and presented 20 or more
times.
Limitations
 As high stimulus intensities are needed to elicit a
detectable behavioral response, it is likely to miss mild
and moderate hearing losses.
HEARING ASSESSMENT
Hearing Testing
Self Test for Hearing Loss
 One can use self administration check list as initial
screen to find out if an audiologic evaluation is
needed.
Hearing evaluation
 The Audiologist will collect information by using case
history form, then otoscopic examination will be
performed to check for any abnormalities in ear
canal. Finally a series of tests are conducted as a part
of detailed evaluation.
HEARING ASSESSMENT
Type of tests used to evaluate hearing
 Pure-tone Audiometry
 Speech Audiometry
 Tests of the Middle Ear
 Auditory Brainstem Response
 Otoacoustic Emissions
PURE-TONE AUDIOMETRY
 Pure-tone Audiometry is a test which is done to get a
qualitative and quantitative analysis of the patients
hearing.
 A pure-tone air conduction hearing test determines
the faintest tones a person can hear at selected
frequencies from low to high.
 Air conduction thresholds for frequencies 125,250,
500,750,1000,1500,2000,3000,4000,6000 and 8000 HZ
are done .
 Bone conduction thresholds for 250, 500, 1000, 2000
and 4000 HZ are done.
 The range of intensities begins at -10dB HL and goes to
110dBHL at frequencies between 500 and 6000HZ, with
slightly lower maximum values at 125, 250, and 8000HZ.
PURE-TONE AUDIOMETRY
 Sounds are presented through earphones or sound
booth.
 A matched pair of earphones is provided and an output
switch directs the tone to either earphone.
 The person can respond by raising a finger or hand,
pressing a button, pointing to the ear where the sound is
received or verbal response of saying “yes” to indicate
that the sound was heard.
 The results are recorded in an audiogram.
 In addition to air- and bone conduction capability, a
masking control is provided that allows for induction of a
noise to the non test ear when needed during
audiometry.
PURE-TONE AUDIOMETRY
 The three important ways in which ambient room noise
may be attenuated are
 A. by using specially designed ear phone enclosures
 B. By testing through receivers that insert into the ear.
 C. By using sound-treated chambers.
Patient Response
 Some audiologists instruct the patients that they can
raise one hand when a tone is heard.
 They can lower the hand when they no longer hear
the tone.
PURE-TONE AUDIOMETRY
PURE-TONE AUDIOMETRY
 The patients can also be instructed to raise their right
hand when they hear tone in the right ear and their
left hand when they hear tone in the left ear.
 The hand signal is the most appropriate response
system used in pure-tone audiometry. In this method
audiologist can observe both how the patient
responds and hearing level that produces the
response.
 Patients can simply raise one index finger when the
tone is heard and lower it when it is not heard, with the
hand signal response system.
PURE-TONE AUDIOMETRY
 The patient can also use signal button with instructions
to press it when the tone is heard and release it when
the tone goes off.
 Pressing the button shows a light on the control panel
of the audiometer and makes a sound.
 Reaction time of the patient is sometimes drawback in
pressing button method.
 Push buttons are not a good idea for children or
physically impaired persons.
 Patients can also choose the option of verbal
response such as saying “yes” or “no” or “I hear it”
whenever tone is heard.
PURE-TONE AUDIOMETRY
False Responses
 They are common during behavioral audiometry.
 Mostly false response occurs when patients fail to
indicate that they have heard a tone. This may lead
to serious errors in the interpretation of test results.
 Some patients might misunderstood or forgotten to
give response. Such false negative responses, tend to
suggest that hearing is worse than it actually is. They
can also seen in patients who feign or exaggerate a
hearing loss.
 False positive responses are where the patient
responds when no tone is presented.
PURE-TONE AUDIOMETRY
Patient’s Position during Testing
 The clinician should not be visible to patient during
pure-tone testing.
 Small eye, hand or arm movements by the clinician
may cause patients to give false responses.
 In one-room testing, patients should be seated so that
they are at right angles to the audiometer.
 Some audiologists might ask patient’s to sit back side
of the audiometer to eliminate any possibility of visual
cues.
PURE-TONE AUDIOMETRY
Procedure for Air-Conduction Audiometry
 Most of the Audiologists prefer to test at 1000HZ
initially, test higher frequencies in ascending order,
retest 1000HZ, and then test lower frequencies in
descending order( 1000, 2000, 4000, 8000,
1000,500,250 HZ, etc.)
 Mostly they take the thresholds only at octave points,
whereas some audiologists prefer the testing of midoctave frequencies (750,1500,3000, and 6000 HZ).
 ASHA(1978) recommends to test mid-octave points
when there is a 20dB difference or more is seen in the
thresholds of adjacent octaves.
PURE-TONE AUDIOMETRY
 Some audiologists used automated pulse tones and
some used manual pulsed tones.
 Descending technique such as whereby the tone is
presented above threshold and lowered in intensity
until patient signals that they can no longer hear it can
be used.
 Ascending technique such as increasing the level of
the tone from below threshold until a response is given
can be used.
 Carhart and Jerger (1959) had implemented several
pure-tone test procedures and found that there were
no real differences in results obtained with different
methods.
PURE-TONE AUDIOMETRY
 The procedure recommended by Carhart and Jerger
is to start testing at 1000HZ as this frequency is easily
heard by most people and has been said to have
high test-retest reliability.
 ASHA (1978) recommends to present a puretone
initially at 30 dBHL. If there is a response, it suggests
that the tone is above the patient’s threshold. If no
response is seen, the level is raised to 50dBHL and then
raise in 10dB steps until a response is seen.
 After a response is obtained lower the level in
10dBsteps.
 Each time a tone is introduced it is maintained for one
or two seconds.
PURE-TONE AUDIOMETRY
 Burk and Wiley (2004) find that automatically pulsed
tones have several advantages such as increased
awareness of the pulsed tones.
 The results of tests done using automated and manual
test tones are similar in terms of false responses, test
reliability , and test time.
 The threshold should be recorded on audiogram.
 After the air-conduction thresholds have been
recorded, the average thresholds for each ear at
500,1000, and 2000HZ should be recorded. This is
called as pure-tone average(PTA).
PURE-TONE AUDIOMETRY
Bone-Conduction Audiometry
 The purpose of bone-conduction audiometry is to identify
the sensorineural hearing loss.
 For many years the bone behind the ear (mastoid
process) was chosen as the most common place for
measuring bone-conduction thresholds.
 This place is chosen because bone-conduction tones are
loudest from the mastoid in persons with normal hearing
and because of each mastoid process’s proximity to the
ear being tested.
 StudeBaker (1962) suggested that the forehead is the best
position for measurement of bone-conduction thresholds
compared to mastoid process.
PURE-TONE AUDIOMETRY
 Some of the consequences of testing on mastoid are
variations produced by vibrator-to-skull pressure,
artifacts created by abnormalities of the soundconducting mechanism of the middle ear and testretest differences.
 The headband used to hold the bone-conduction
vibrator is much comfortable to use on head
compared to mastoid process.
 The main disadvantage of forehead testing is that
about 10dB greater intensity is required to stimulate
normal thresholds which results in a decrease of
maximum level at which testing can be carried out.
PURE-TONE AUDIOMETRY
Procedure for Bone-Conduction Audiometry
 The procedure is same as air-conduction audiometry.
 Any ear can be tested first without a preference.
 Bone-conduction thresholds are recorded in same
fashion to those for air conduction using the correct
spaces on audiometric work sheet.
 The symbol for forehead bone conduction is a black V
when no masking is used.
 For the mastoid testing, a red arrowhead pointing to
the reader’s left is used for the right ear and a blue
arrowhead pointing to the reader’s right for the left
ear.
PURE-TONE AUDIOMETRY
The most techniques which are used with young
children are
1.
Visual reinforcement audiometry
2.
Conditioned play audiometry
PURE-TONE AUDIOMETRY
Visual reinforcement audiometry
 It is method used for screening children between 6
months to 2 years of age.
 The training is given to child so that they look towards
a sound source.
 The response is rewarded through a visual
reinforcement.
 When the child looks at sound source he gets a
reward such as watching toy or flashlight.
PURE-TONE AUDIOMETRY
 Watch the following video on Visual Reinforcement
Audiometry from NHS forth Valley
PURE-TONE AUDIOMETRY
Conditioned play audiometry
 It is used with toddlers and preschoolers between
ages 2-5.
 The child is trained to perform an activity each time a
sound is heard.
 The activity may involve putting a block in box,
placing pegs in a hole or putting a ring on a cone.
PURE-TONE AUDIOMETRY
 Watch the following video on conditioned play
audiometry
SPEECH AUDIOMETRY
 Speech tests are administered as part of hearing testing.
 Speech Reception Threshold (SRT) is the most commonly
used speech test.
 SRT is the low intensity in decibels at which patient can
understand 50% of the words from the presented list.
 Word recognition and repetition of words is recorded at
a comfortable loudness level.
 Conducting these tests are important as difficulty
understanding speech in background noise is a
common complaint of people with hearing loss.
SPEECH AUDIOMETRY
Test Environment
 Most speech audiometry is conducted with the
patient sitting in one or two sound treated room.
Examiner and the patient sit in separate rooms.
 If they are seated in same room it will be difficult to
check whether the patients are responding to sounds
channeled to them through the audiometer or directly
through the air in the room.
 Recorded material can be used which provide a
consistency of presentation that is independent of the
expertise of the clinician.
SPEECH AUDIOMETRY
Speech-Detection Threshold (SDT)
 It is defined as the lowest level in decibels at which a
subject can barely detect the presence of speech
and identify it as speech.
 The SDT is also called the speech-awareness threshold
(SAT).
 SDT can be measured by presenting through the
output transducer and some continuous discourse.
 The level of speech is raised and lowered in intensity
until the patient indicates that he or she can barely
hear the speech.
SPEECH AUDIOMETRY
 For SDT, sentences are preferred to isolated words and
phrases.
 The sentences should be presented rapidly and
monotonously so that there are few peaks above and
below zero on the UV meter.
 Patients can respond verbally with hand or finger
signals or with a push button indicating the lowest
level in dbHL.
SPEECH AUDIOMETRY
Speech-Recognition Threshold (SRT)
 It can be defined as the lowest hearing level at which
speech can barely be understood.
 Speech should be soft enough to recognize.
 SRT is the most popular test used by audiologists.
 Spondiac words are used in SRT.
 A spondee is a word with two syllables which is
pronounced with equal stress and effort.
SPEECH AUDIOMETRY
 The ASHA (1989) suggested following steps for
determining SRT
 Familiarize the listener with the spondaic words in the
word list to be used.
 Ensure that the vocabulary is familiar.
 Establish that each word can be recognized auditorily.
 Ascertain that the patient’s responses can be
understood by the clinician.
SPEECH AUDIOMETRY
Procedure for obtaining SRT (Martin and Dowdy ,1986)
 Start at 30dbHL and present one spondee. If there is a
response this suggests that the word is above the
patient’s SRT.
 If there is no response, raise the presentation level to
50dBHL.Then present one spondee. If there is no correct
response raise the intensity in 10 dB steps, presenting one
spondee at each increment. Continue the procedure
until you get one correct response.
 After a correct response, lower the intensity by 10dB.
 When a incorrect response is seen, raise the level by 5dB
and if the response is correct lower it by 10dB.Continue
the procedure until you get a correct response.
SPEECH AUDIOMETRY
 From this point on the intensity is increased in 5dB steps
and decreased in 10dB steps, with one spondee
presented at each level until three correct responses
are obtained at a given level.
 Threshold is defined as the lowest level at which at
least 50 percent of the responses are correct, with a
minimum of at least three correct responses at that
intensity.
TESTS OF THE MIDDLE EAR
 The middle ear tests are done to check how the
middle ear is functioning.
 Immitance audiometry is the term used to encompass
a battery of three tests:
1.Tympanometry
2.Acoustic reflex testing
3.Static acoustic impedance.
 This type of testing is important in preschool children
ages 3-5 for whom hearing loss is associated with
middle ear disease.
TESTS OF THE MIDDLE EAR
 Tympanometry
TESTS OF THE MIDDLE EAR
TYMPANOMETRY
 It is technique for measuring relative changes in the
compliance of the tympanic membrane as air pressure is
mechanically varied in the external auditory canal.
 The compliance at specific air pressures is plotted on a
graph known as a tympanogram.
 The pattern of tympanogram provides information
regarding the status of middle ear.
 For example , a tympanogram may suggest normal
middle ear function, the presence of middle ear effusion,
eustachian tube dysfunction, ossicular fixation or
discontinuinty.
TESTS OF THE MIDDLE EAR
ACOUSTIC REFLEX TESTING
 The acoustic reflex threshold represents the lowest
stimulus intensity level at which a contraction of
stapedius muscle in the middle ear is detectable as a
change in tympanic membrane compliance.
 Thresholds are obtained for octave frequencies of 500
to 4000 HZ.
 Acoustic reflex thresholds can provide considerable
information regarding presence or absence of middle
ear pathology in the ear where reflex is measured
and the type of hearing loss (conductive or
sensorineural) in the ear receiving the stimulus.
TESTS OF THE MIDDLE EAR
STATIC ACOUSTIC IMPEDANCE
 It measures the physical volume of air in the ear canal.
 The test is useful in identifying a perforated eardrum or
checking the openness of ventilation tubes.
 It is the mobility of tympanic membrane in response to
a given value of air pressure in the external ear canal.
AUDITORY BRAINSTEM RESPONSE
(ABR)
AUDITORY BRAINSTEM RESPONSE
(ABR)

The auditory brainstem response (ABR) test gives information about
the inner ear and brain pathways for hearing.

The test can be used with children or others who have difficult time
with conventional behavioral methods of hearing screening. It is the
most popular technique for screening the hearing of neonates.

The ABR consists of seven components of the auditory evoked
response that occur within the first 10 milliseconds after stimulus onset.

The term auditory evoked response refers to changes in the ongoing
electrical activity of the brain that occur in response to auditory
stimulation. The changes are extremely small and cannot be
detected without using of signal-averaging computers.

It is performed by pasting electrodes on head and recording brain
wave activity in response to sound. The person being tested sleeps
while the test is performed.

It is used as a screening test in newborn babies where only one
intensity is checked and the baby either passes or fails the screen.
OTOACOUSTIC EMISSIONS
(OAE’S)
OTOACOUSTIC EMISSIONS
(OAE’S)
 Otoacoustic emissions are sounds given off by the inner
ear when the cochlea is stimulated by a sound. When the
sound stimulates the cochlea, the outer hair cells vibrate.
The vibration produces a inaudible sound that echoes
back into the middle ear. They can be elicited with clicks.
 The sound is measured with a small probe inserted in to
the ear canal.
 People with normal hearing produce emissions. Those
with hearing loss greater than 25-30 decibels do not
produce these very soft sounds.
 It is very useful to identify hearing loss in newborns.
 The test can detect blockage in the outer ear canal,
presence of middle ear fluid and damage to outer hair
cells in cochlea.
References
 Images
Otoacoustic emisisons (n.d.). Retrieved November 10,
2013 from
http://www.etymotic.com/pro/oaets.aspx
Tympanometry (2013). Retrieved from
http://lawoto.com/?page_id=186
Auditory brainstem response (n.d.). Retrieved November
10, 2013
from http://www.discoverbetterhearing.com.my/auditory
-brainstem-response.php