This document provides information on performing and interpreting basic hearing evaluations through audiometric testing. It discusses how to conduct puretone audiometry to test air and bone conduction thresholds and speech testing to obtain the speech reception threshold and word recognition score. These results are used to determine the type, degree, and configuration of any hearing loss. Conductive losses involve the outer/middle ear and show normal bone conduction with an air-bone gap. Sensorineural losses involve the inner ear/auditory nerve and show elevated air and bone conduction thresholds with no gap. Mixed losses combine both conductive and sensorineural components. Proper interpretation of an audiogram is important for medical diagnosis and treatment recommendations.

1. Ozarks Technical Community College
HIS 125

2. You can’t fit a hearing aid until you
can perform/interpret audiograms!

Being able to perform an accurate
hearing test and interpret the obtained
results are imperative to:
 Making appropriate recommendations
○ Is a medical referral required?
○ Amplification options
○ Hearing aids versus cochlear implant?
 Fitting hearing aids appropriately!

3. Basic Hearing Evaluation

Audiogram
 Puretone audiometry
○ Air-conduction (AC) and bone-conduction (BC) testing
 Speech audiometry
○ Speech reception threshold (SRT)
 This may also be called speech recognition threshold
○ Word recognition score (WRS)
 This may also be called speech discrimination score
 The goal is to determine
○ How well you hear
○ How clearly you hear speech
○ If there is a medical reason for hearing loss
○ If there is a need for some sort of intervention

4. Hearing Loss is defined by…

Type of Loss
 Conductive
 Sensorineural
 Mixed

Degree of Loss
 Normal, mild, moderate, moderately-
severe, severe, profound

Configuration of Loss
 Flat, sloping, rising, etc.

5. Puretone Audiometry
Recall that human ears have an audible
bandwidth (frequency range) of 20 to
20,000 Hz
 In audiometric testing, the stimuli are
puretones from 250 to 8000 Hz.

 Why?
○ because human speech falls within these
frequencies
 Most commonly octave bands at
250, 500, 1000, 2000, 4000, and 8000 Hz are
tested
 The interoctave frequencies of 3000 and 6000
Hz are also commonly tested in adults

6. Puretone Audiometry

Air-conduction testing
 Performed with headphones or insert earphones
 Takes into account the entire auditory pathway
○ Outer ear, middle ear, inner ear, nerve, brain

Bone-conduction testing
 Performed with a bone-conduction oscillator
placed on either mastoid bone (most common)
or the forehead
 Directly stimulates the inner ear and nerve
○ Bypasses the outer and middle ear

7. Puretone Audiometry


Threshold is the softest sound that a listener
can hear 50% of the time
A bracketing technique is used to establish
threshold.
 Remember…down 10, up 5.
 If the patient responds, reduce the stimulus intensity
by 10 dB. If no response, increase intensity using 5
dB steps. Repeat this procedure until you find
threshold.


I prefer to start testing at 1000 Hz at 50 dB HL.
I always use a pulsed puretone, as it is
preferred for patient’s with tinnitus.

8. Normal Hearing



Normal AC and BC
thresholds
Many different
scales exist
regarding degree of
HL
For the purposes of
this class, we will
use the scale on the
next slide.

9. Degree of Hearing Loss

This is the exact scale
that I use in interpreting
audiograms
 Some clinics are more
liberal and consider
normal hearing to be any
threshold up to 25 dBHL

In determining the
degree of loss, the
textbook approach
would be to calculate
the puretone average
(PTA=average dB of AC
thresholds at .5, 1, 2
kHz) and compare the
PTA to the scale at right.
From: Northern, J. Hearing Disorders (3rd ed)

10. Speech Audiometry

Speech reception threshold (SRT)
 The softest level (dB HL) at which a patient can
accurately repeat spondees (two-syllable words;
i.e. baseball, hotdog, birthday) 50% of the time
○ Uses the same bracketing technique as puretone
testing
 SRT is primarily used as a reliability check
○ In comparing the SRT to the PTA, they should be
within 10 dB of each other
○ If you have poor SRT-PTA agreement, then the
reliability of your results should be considered to
be questionable

11. Speech Audiometry

Word recognition score (WRS)
 The percentage of phonetically-
balanced, monosyllabic words that a patient can
accurately repeat
 Presented at either MCL (most comfortable level) or
MIL (most intelligible level)
○ This is generally thought to be approximately 40 dB
above the SRT
 A pre-recorded list of 25 to 50 words should be
presented to each ear
 Each word should be preceded by a carrier phrase:
○ “Say the word pick”
○ “Say the word room”

12. WRS in determining site-oflesion




Patient’s with normal hearing or conductive
hearing loss will perform normally on WR
testing
Patient’s with only high-frequency or a
mild, flat SNHL will also generally perform
near-normal
The more severe the SNHL, the poorer a
patient will perform on WR testing
Neural losses result in poor performance
 Asymmetrical WRS, especially in the presence of
puretone asymmetries, should be considered a “red
flag” for an acoustic neuroma
 In patient’s with a retrocochlear lesion, roll-over may
also be present on WR testing. This means that with
increased presentation level, the patient’s
performance will actually decrease (i.e. 56% at 85
dB decreasing to 12% at 95 dB).

13. Audiometric Interpretation
If a patient has a disorder of the outer
and/or middle ear ONLY, then AC
thresholds will be abnormal in the
presence of normal BC thresholds
 Air-bone gap = greater than or equal to
15dB difference between AC and BC
 This is called a conductive hearing
loss, as sound cannot properly conduct
through the outer and/or middle ear to
reach the normal-hearing cochlea


14. Some Causes of CHL









Anotia
Microtia
Atresia
Outer ear infection
Middle ear infection
Otosclerosis
Dislocation of the middle ear bones
Cholesteatoma
Ear wax!

15. Conductive Hearing Loss


Normal BC thresholds
Abnormal AC thresholds
 An air-bone gap is present
at .5, 1, 2, and 4 kHz

WRS should be nearly
normal, as there is no
damage to the
cochlea/nerve

*Note: recall that dB SL refers
to sensation level, which is
the intensity that is added to
threshold. When performing
WRS, the presentation level
should be at the most
comfortable/intelligible level
for the patient. This level is
generally thought to be the
SRT + 35-40 dB SL. So in the
example at right, the WR
testing was performed at 65
dB HL.
This patient has a mild CHL
Image from: telemedicine.orbis.org

16. Audiometric Interpretation
If a patient has a disorder of the inner
ear and/or auditory nerve, then AC
thresholds will be equal to BC
thresholds (no air-bone gap) and both
will be abnormal
 This is called a sensorineural hearing
loss


17. Some Causes of SNHL
Aging (presbycusis)
 Noise Exposure
 Genetics
 Acoustic Neuroma
 Meniere’s Disease
 Ototoxic Drugs


18. Sensorineural Hearing Loss





Abnormal AC and BC
thresholds
No air-bone gap
WRS will vary
depending on degree of
loss and cochlear vs.
neural damage
According to the PTA
method of determining
degree of HL, this
patient has a slight
SNHL.
However, due to the
sloping configuration, I
prefer to define the loss
as a slight-sloping-tosevere SNHL. It is more
accurate.
Image from: telemedicine.orbis.org

19. Puretone Audiometry
Interpretation
If a patient has a disorder of the inner
ear and/or auditory nerve AND an
outer/middle ear disorder, then both AC
thresholds and BC thresholds will be
abnormal AND an air-bone gap will exist
 This is called a mixed hearing loss
 Example: 75 yo, male with age-related
hearing loss and bilateral otitis media


20. Mixed Hearing Loss




Abnormal AC and BC
thresholds
Air-bone gap present
Expected WRS based
on BC thresholds
This patient has a mild
to moderately-severe
MHL.
Image from: telemedicine.orbis.org

21. Always keep these FDA
Regulations in mind…

If any of the following conditions exist, a patient
must be referred for a medical evaluation by a
physician (preferably an ENT):
 Visible congenital or traumatic deformity of the ear.
 History of active drainage from the ear in the previous 90






days.
History of sudden or rapidly progressive hearing loss
within the previous 90 days.
Acute or chronic dizziness.
Unilateral hearing loss of sudden or recent onset within
the previous 90 days.
Audiometric air-bone gap equal to or greater than 15
decibels at 500 Hz, 1,000 Hz, and 2,000 Hz.
Visible evidence of significant cerumen accumulation or a
foreign body in the ear canal.
Pain or discomfort in the ear.