ComD 3700 Course Notes-Lesson 1

ComD 3700 Course Notes-Lesson 1
ComD 3700 Course Notes-Lesson 1
4/19/11 11:08 PM
Lesson 1
The Profession of Audiology
PowerPoint Overview:
History of Audiology
Product of WWII
Dr. Raymond Carhart coined the term
“Father of Audiology”
Grew out of 2 major professional areas:
1. Medical and medically related professions:
Gerontology
Pediatrics
Neurology
Neurosurgery
Psychiatry
2. Non-Medical professions:
Speech-Language Pathology
Physics
Education
Biology
What is an Audiologist?
A qualified well-trained professional who has the knowledge and skills to
diagnose, manage, and treat infants through adults with a comprehensive
array of services related to auditory and vestibular disorders
An individual who, “by virtue of academic degree, clinical training and license
to practice and/or professional credential, is uniquely qualified to provide a
comprehensive array of professional services related to…the audiologic
identification, assessment, diagnosis, and treatment of persons with
impairment of auditory and vestibular function, and to the prevention of
impairments associated with them” (American Academy of Audiology, 2004).
Academic Requirements
Doctor of Audiology (AuD) Degree from an accredited academic program or
school and pass a national examination.
Why was this necessary?
Profession is too sophisticated to prepare for in 2 years
Mandated by ASHA
Clinical doctorate (Au.D.)
Research doctorate (Ph.D.)
Audiologists are licensed in every state and the District of Columbia
Is the education worth it?
Audiology Work Settings
Audiologists work as an independent practitioner providing hearing and
balance services in a wide variety of settings.
These include:
Private Practices
Hospitals
Medical Clinics
Schools (Educational Audiology)
Rehabilitation Centers
ENT/Physicians Offices
Academia
Manufacturing Facilities
Uniformed and Government Services
Industrial Audiology
What do audiologists do?
Conduct a broad range of testing to determine the exact nature of a person’s
hearing or balance problems
Present a variety of options to patients
Dispense and fit hearing aids and other assistive technologies
Coordinate hearing conservation programs in industry
Work as members of cochlear implant teams
Provide clinical and academic training to students in audiology
Develop infant hearing screening programs
Serve as expert witnesses within the boundaries of forensic audiology
Provide habilitation and rehabilitation to patients with hearing and balance
impairments
Serve as a source of information for family members, other professionals,
and the general public on hearing and balance disorders and treatment
Types of Hearing Tests
Otoscopy
Tuning fork tests
Immittance (middle ear analysis)
Pure tone hearing (AC/BC)
Speech Testing
Otoacoustic emissions
Auditory Brainstem Response
Special Testing
Average Salary of an Audiologist
Based on geographic location:
Northeast
$57,000
Midwest
$52,500
South
$52,000
West
$55,000
Metropolitan
$55,000
Suburban
$52,000
Rural
$50,500
Average Salary of an Audiologist
Based on years in workforce:
1-3 yrs
$42,000
4-6 yrs
$46,000
7-9 yrs
$50,000
10-15 yrs
$56,000
19-21 yrs
$65,500
22-27 yrs
$68,000
28 + yrs
$84,500
Why I enjoy audiology…
Growing & Evolving Profession
Variety
Patient centered profession
The blending of the science of audiology with the art of patient treatment
makes audiology a highly rewarding profession. It is the humanistic side of
our professional endeavors that not only brings audiologists close to the
patients & families they serve but makes the outcomes of provided services
rewarding for both the practitioner and the recipient of care. (Clark &
English, 2004)
Opportunities for cerumen removal!
Is Audiology for Me?
Personality
Motivation
Future of the field
Projected need for audiologists
Hearing loss the 3rd major common chronic condition
Level of required education
I want to be a SLP, why does this matter?
Audiology and SLP share a common heritage and professional society, the
American Speech-Language Hearing Association (ASHA)
Frequent coexistence of hearing disorders & speech/language disorders
Important that speech-language pathologists have a working knowledge of
audiology
SLP’s often work closely with audiologists
Hearing loss can have a direct impact in speech and language development
SLP Scope of Practice
According to ASHA, the speech-language pathologist’s scope of
practice includes:
Hearing screening procedures
Therapeutic aspects of audiologic rehabilitation
Basic checks of hearing aid performance
Informational Websites
http://www.asha.org/careers/professions/audiology.htm Fact Sheet for
Audiology
http://www.asha.org/careers/professions/hla.htm Hearing Loss and the
Audiologist
http://www.explorehealthcareers.org/en/Career.58.aspx Exploring Health
Careers
http://www.asha.org/aud/pediatric-ed.htm Pediatrics
http://www.asha.org/aud/private.htm Private Practice
http://www.asha.org/aud/occupational.htm Occupational Health
http://www.asha.org/members/international/intlfaqs.htm International FAQs
http://www.asha.org/careers/professions/WorkingAbroad.htm Working
Abroad
http://www.bls.gov/oco/ocos085.htm Occupational Outlook Handbook
http://www.asha.org/careers/professions/trends.htm Trends
http://www.asha.org/careers/professions/EmploymentSettings.htm
Employment Settings
http://www.asha.org/uploadedFiles/research/09AudiologySupplyDemand.pdf
Supply and Demand for Audiologists 2009
http://www.asha.org/aud/faq_aud.htm Audiology FAQs
http://www.asha.org/research/memberdata/AudiologySurvey.htm Audiology
Survey
http://www.asha.org/aud/pei.htm Patient Education Materials
http://www.audiology.org/education/students/SAA/Pages/default.aspx SAA
Textbook Chapter 1 Overview:
Learning Objectives
The purpose of this opening chapter is to introduce the profession of
audiology, from its origins, through its course of development, to its present
position in the hearing-health-care-delivery system. At the completion of
this chapter, the reader should be able to:
Describe the evolution of audiology as a profession.
Discuss the impact of hearing impairment on individuals and society.
List specialty areas within audiology and the employment settings within
which audiologists may find themselves.
Describe the reasons that speech-language pathologists may interact closely
with audiologists as they provide services within their chosen professions.
Summary
Compared to other professions in the health arena, audiology is a relative
newcomer, emerging from the combined efforts of otology and speech
pathology during World War II. Following the war, this new area of study
and practice grew rapidly within the civilian sector because of the high
prevalence of hearing loss in the general population and the devastating
effects on individuals and families when hearing loss remains untreated. To
support the needs of those served fully, especially the pediatric population,
audiologists often maintain close working relationships with speech-language
pathologists and educators of people with hearing impairment. A mutual
respect for what each profession brings to auditory (re)habilitation leads to
the highest level of remediation for those served.
Today the profession of audiology supports a variety of specialty areas and
is transitioning toward a professional doctorate as the entry-level degree.
Given projected population demographics, students choosing to enter this
profession will find themselves well placed for professional growth and
security.
Outline
The evolution of audiology
Prevalence and impact of hearing loss
Audiology specialties
Employment settings
Professional societies
Vocabulary
American Academy of Audiology (AAA)
American Speech-Language-Hearing
Association
(ASHA)
Audiology
Aural rehabilitation
Industrial audiology
Medical audiology
Otology
Pediatric audiology
Rehabilitative audiology
ComD 3700 Course Notes-Lesson 2
4/19/11 11:08 PM
Lesson 2
The Human Ear & Simple Tests of Hearing
PowerPoint Overview:
Anatomy & Physiology of the Ear
Pathways of Sound
Types of Hearing Loss
Conductive Hearing Loss
Sensorineural Hearing Loss
Mixed Hearing Loss
Nonorganic Hearing Loss
Conductive Hearing Loss
Involves the breakdown or obstruction of some part of the external or
middle ear only
The physical vibrations of sound are no longer transmitted or conducted
through air conduction because of the obstruction
Most problems are medically correctable
Physical conduction of sound to sensory organ
Bone conduction test results will be normal
Sensorineural Hearing Loss
Results in damage occurring in the inner ear
Damage to cochlea and/or VIII Cranial Nerve (CN)
Sensory loss involves only the cochlea
Neural involves only the VIII CN
Usually referred to as combined-sensorineural hearing
Same amount of hearing loss for both air and bone conduction testing
Mixed Hearing Loss
A combination of conductive and sensorineural hearing loss, occurring
simultaneously in the same ear
Air conduction results will be worse than bone conduction results
Nonorganic Hearing Loss
Often called a “Functional Loss”
A result of some sort of psychological cause
There is nothing wrong with the hearing mechanism
No known organic cause
Types of nonorganic hearing loss:
Malingering-Patient willingly & knowingly fabricates a hearing loss for some
sort of gain
Conversion hysteria-Patient cannot hear, but there is not evidence of organic
cause
Psychogenic hearing loss-Some psychological disorder that manifests in the
symptoms of hearing loss
Tuning Fork Tests
Tuning forks were used to test hearing long before electronic
instrumentation came along
Four of the more well known of these tests are:
The Schwabach
The Rinne
The Bing
The Weber
The tuning fork is set into vibration by holding the stem in the hand and
striking he tines against a firm but resilient surface such as the rubber heel
of a shoe.
Tuning fork tests are no where near as accurate, qualitative or quantitative
as audiometric testing
We discuss them to help us understand certain principles as to the pathways
of hearing and the nature of certain types of hearing loss
It is also important to know how to perform them, especially the Rinne and
Weber, as they are still used by some audiologists, otologists and ENT
physicians as a cross check measure in separating conductive from
sensorineural hearing loss
The Schwabach Test
A bone conduction test comparing the hearing sensitivity of the patient with
the examiner
The procedure is to strike and place the tuning fork on the patients mastoid
bone
When the patient can no longer hear the tone, the tuning fork is placed on
the examiners ear and timed as to how long he can hear it.
The assumption that the examiner has normal hearing, is one reason the
test is rarely used today
The Schwabach Test Results
Normal Schwabach=Normal hearing = patient hears for same length of time
Diminished Schwabach=Sensorineural HL = patient hears for shorter time
Prolonged Schwabach=Conductive HL = patient hears for longer time
A principle to keep in mind:
An impairment of the conductive hearing mechanism will enhance one’s
bone conducted perception of sound
The Rinne Test
This test compares hearing by air conduction to hearing by bone conduction
This air conduction advantage is lost whenever there is a conductive hearing
loss, in which case the tuning fork will sound louder by bone conduction than
by air conduction
To perform the test, the fork is struck and alternately placed on the mastoid
bone (BC) and at the opening of the ear canal (AC).
The patient is asked if the tone is louder with mastoid placement or ear
canal placement
Masking must be placed in the non-text ear to make sure the tone is being
heard in the test ear.
The Rinne Test Results
Rinne Positive-when the fork is heard louder at the ear canal and this
indicates either normal hearing acuity or a sensorineural hearing loss
Rinne Negative-when the fork is heard louder at the mastoid and indicates a
conductive hearing loss
A false negative Rinne -when there was not sufficient mask and the test tone
crossed the head and was heard in the non-test ear
The following principle is vital to understanding this test:
The hearing mechanism is normally more sensitive by air conduction than by
bone conduction
The Bing Test
Takes advantage of the occlusion effect
When the ear canal is occluded or when a conductive hearing disorder is
present, there is an enhanced perception of a tone when delivered to the
inner ear via bone conduction
The Bing Test Results
Positive Bing-If a person has normal or sensorineural hearing loss, they will
hear the tone from the tuning fork when the examiner occludes the outer
ear by pushing in on the tragus therefore occluding the outer ear.
Negative Bing-If the person already has a conductive hearing loss, pressing
and releasing the tragus will not effect a change in the patient’s perception
of the tone.
The Weber Test
The Weber test is used to tell whether a unilateral hearing loss is conductive
or sensorineural
It is a test of lateralization because the patient is asked to indicated from
which direction the sound seems to be coming
The patient indicates which ear is the poor ear and which ear is the better
ear
The tuning fork is placed on the forehead & the patient is asked where they
hear the tone
The Weber Test Results
If the tone is heard in the better ear-then the poorer ear must be a
sensorineural hearing loss
If the tone is heard in the poorer ear-that ear must have a conductive
hearing loss
Textbook Chapter 2 Overview:
Learning Objectives
The purpose of this chapter is to present a simplified explanation of the
mechanism of human hearing and to describe tuning-fork tests that provide
information about hearing disorders. Because of the structure of this
chapter, some of the statements have been simplified. These basic concepts
are expanded in later chapters in this book. Upon completion of this
chapter, the reader should be able to:
Develop a basic vocabulary of terms related to the ear.
Understand the core background for study of more sophisticated hearing
tests.
Describe the general anatomy of the hearing mechanism and its pathways of
sound.
List and describe the three types of hearing loss presented.
Outline the expected tuning fork test results for different types of hearing
loss.
Summary
The mechanisms of hearing may roughly be broken down into conductive
and sensorineural portions. Tests by air conduction measure sensitivity
through the entire hearing pathway. Tests by bone conduction sample the
sensitivity of the structures from the inner ear and beyond, up to the brain.
The Schwabach test compares the bone-conduction sensitivity of the patient
to that of a presumed normal-hearing person (the examiner); the Rinne
tuning-fork test compares patients’ own hearing by bone conduction to their
hearing by air conduction in order to sample for conductive versus
sensorineural loss; the Bing test samples for conductive hearing loss by
testing the effect of occluding the ear; and the Weber test checks for
lateralization of a bone-conducted tone presented to the midline of the skull
to determine if a loss in only one ear is conductive or sensorineural.
Outline
Anatomy and physiology of the ear
Pathways of sound
Types of hearing loss
Hearing tests
Tuning fork tests
Vocabulary
Air conduction
Attenuation
Auditory
Auditory nerve
Bing test
Bone conduction
Cochlea
Conductive hearing loss
Eardrum membrane
Hearing loss
Inner ear
Lateralization
Mastoid process
Middle ear
Mixed hearing loss
Occlusion effect
Outer ear
Rinne test
Schwabach test
Sensorineural hearing loss
Stenger principle
Tuning fork
Weber test
ComD 3700 Course Notes-Lesson 3
4/19/11 11:08 PM
Lesson 3
The Measurement of Sound
PowerPoint Overview:
Acoustics Review
Waves
Vibrations
Frequency
Resonance
Sound Velocity
Wavelength
Phase
Complex Sounds
Intensity
Physical attributes of Sound
Sound is a form of energy
It is a wave disturbance that travels through any medium
Sound differs from other vibrating motion in that sound waves in free air are
three dimensional
Three properties are necessary to produce sound waves:
A Force
A Vibrating Mass
An Elastic Medium
Sound in air is propagated as a longitudinal wave
Sound and its Measurement
Sound may be regarded objectively if we consider its waves in terms of their
frequency, intensity, phase, and spectrum.
Sounds may also be studied subjectively, in terms of pitch, loudness, or the
interactions of signals producing masking or localization.
In discussing sound energy it is always important to specify precisely the
various aspects and appropriate measurement references, such as hertz,
decibels (IL, SPL, HL, or SL), mels, sones, or phons.
Intensity and pressure are two different ways of looking at the same sound
wave.
The Decibel (dB)
Developed by Alexander Graham Bell
A tenth of a Bel
Measurement unit for intensity (loudness)
A dimensionless number that is the log of a ratio of two powers or pressures.
It’s exponential.
Usually measured in a range of 0 to 140 dB
No fixed absolute value
Measurement of intensity used in acoustics and audiometry
Acoustic Reference
Important to develop or define:
beginning point
zero point
threshold
How cold is cold?
How soft is soft?
Reference of Zero
Zero dB does not mean the absence of sound.
It means the amount of sound pressure you are comparing is equal to the
reference level and no pressure increase occurs
Lowest point in intensity that a person can perceive the stimulus
Measured in various ways:
Intensity Level (IL)
Sound Pressure Level (SPL)
Hearing Level (HL)
Sensation Level (SL)
Intensity Level
Intensity is the amount of energy transmitted per second over an area of 1
square meter. There is an absolute measure and a relative measure
The unit of measure for intensity is the watt per square meter (watt/m2)
Absolute measure of acoustic power in watts is the rate at which energy is
consumed.
Intensity level only exists where there is a reference given. Therefore dB IL
should only be used when the reference is 10-12 watt/m2 under standard
conditions (200 centigrade and barometric pressure of 760 mm mercury).
The usual intensity reference (IR) is :
IR = 10-12 watt/m2 = 10-16 watt/cm2
The most common approach to sound intensity measurement is to use the
decibel scale:
dB = 10 x log (I0/IR)
If the intensity output (I0) and the intensity reference (IR) are exactly the
same (I0=IR) then the ratio is 1:1.
1:1 ratio=Log 0= 10-16 watt/cm2=0 dB IL
Sound Pressure Level
Most common usage of decibels in reference to the nominal threshold of
human hearing
Pressure is defined as a force per unit area
A unit of force is a Newton (N)
One Newton (N) is a force that will accelerate one kilogram (kg) of mass
(Mass) a distance of one meter (Distance) per second (Time)
A unit of sound pressure is called a Pascal (Pa)
One Pascal is equal to one Newton per square meter or 1 Pa = 1 N/M2
The smallest sound pressure variation required to produce a just audible
sound to healthy young ears is approximately:
0.00002 Pa or 20 µ Pa
µ = 1 millionth part of
0 dB SPL = 20 µ Pa
Audiogram
dB Sound Pressure Level (SPL)
dB HL to dB SPL
0 dB HL at 125 Hz = 47.5 SPL
0 dB HL at 250 Hz = 26.5 SPL
0 dB HL at 500 Hz = 13.5 SPL
0 dB HL at 1000 Hz = 7.5 SPL
0 dB HL at 2000 Hz = 11.0 SPL
0 dB HL at 4000 Hz = 10.5 SPL
0 dB HL at 8000 Hz = 13.0 SPL
Hearing Level (HL)
Sensation Level (SL)
Auditory threshold of an individual
Term used to designate an intensity level above threshold
You have to know the patient’s threshold before you can identify the SL level
If I said, “present a stimulus to the patient at 20 dB SL at 1000 Hz” and the
patient’s threshold at 1000 Hz was 25 dB HL. The stimulus would be
presented to the patient at 45 dB HL.
Reference Levels
A decibel is a ratio that does not have an absolute or fixed value, it always
has a reference level.
Reference levels are:
dB IL=
10-12 watt/m2 or 10-16 watt/cm2
dB SPL=
20 micropascals (µ Pa) or 0.0002 dyne/cm2
dB HL=
Audiometric Zero-ANSI standards
dB SL=
The patient’s threshold
Textbook Chapter 3 Overview: (**Use this for Lesson 3 and 4***)
Learning Objectives
Understanding this chapter requires no special knowledge of mathematics or
physics, although a background in either or both of these disciplines is surely
helpful. From this chapter, readers should be able to:
Describe sound waves and their common attributes and express the way
these characteristics are measured.
Discuss the basic interrelationships among the measurements of sound and
be able to do some simple calculations (although at this point it is more
important to grasp the physical concepts of sound than to gain skill in
working equations).
Have an understanding of the different references for the decibel and when
they are used.
State the difference between physical acoustics and psychoacoustics.
Discuss the reasons for audiometer calibration and in general terms what
this may entail.
Summary
Sound may be regarded objectively if we consider its waves in terms of their
frequency, intensity, phase, and spectrum. Sounds may also be studied
subjectively, in terms of pitch, loudness, or the interactions of signals
producing masking or localization. In discussing sound energy it is always
important to specify precisely the various aspects and appropriate
measurement references, such as hertz, decibels (IL, SPL, HL, or SL), mels,
sones, or phons.
Outline
Sound
Waves
Vibrations
Frequency
Resonance
Sound velocity
Wavelength
Phase
Complex sounds
Intensity
The decibel
Environmental sounds
Psychoacoustics
Impedance
Sound measurement
Vocabulary
Amplitude
Anechoic chamber
Logarithm
Longitudinal wave
Aperiodic wave
Artificial ear
Artificial mastoid
Audiometer
Beats
Bel
Brownian motion
Cancellation
Complex wave
Component
Compression
Loudness
Mel
Microbar (µbar)
Newton (N)
Octave
Ohm (Ω)
Oscillation
Overtone
Pascal (Pa)
Period
Periodic wave
Cosine wave
Cycle
Damping
Decibel (dB)
Difference tone
Dyne (d)
Elasticity
Erg (e)
Exponent
Force
Forced vibration
Formant
Fourier analysis
Free field
Free vibration
Frequency
Fundamental frequency
Harmonic
Hearing level (HL)
Hertz (Hz)
Impedance
Intensity
Intensity level (IL)
Inverse square law
Phase
Phon
Pitch
Potential energy
Power
Pressure
Pure tone
Quality
Rarefaction
Ratio
Reactance
Resistance
Resonance
Resonant frequency
Reverberation
Sensation level (SL)
Sine wave
Sinusoidal
Sone
Sound-level meter
Sound-pressure level (SPL)
Spectrum
Stiffness
Stiffness reactance
Joule (J)
Kinetic energy
Localization
Loudness level
Masking
Mass
Mass reactance
Threshold
Transverse wave
Velocity
Vibration
Watt
Wave
Wavelength
Work
ComD 3700 Course Notes-Lesson 4
4/19/11 11:08 PM
Lesson 4
The Measurement of Sound
PowerPoint Overview:
Psychoacoustics Review
Pitch-Psychological measurement of whether a sound is high or low
1000 Mels is the pitch of a 1000 Hz tone at 40 dB SL
Loudness-Subjective or psychological experience
Phons compare loudness levels across frequencies
Corresponds to the loudness of a signal at other frequencies equal to the
intensity of a 1000 Hz tone
40 dB SPL at 1000 Hz equals 40 phons
Sones measure loudness up the frequency
One sone equals the loudness of a 1000 Hz tone at 40 dB SPL
In normal ears, this is also 40 phons
Sound Measurement
Audiometers
Made by a number of manufacturers
Vary in complexity and control layout
Controls or indicators may be dials, buttons or switches
Every audiometer usually has the following:
Supra-aural and/or insert earphones and a bone receiver
Hearing Level indicator or attenuator
Frequency Indicator
Ear Indicator
Interrupter switch
Basic Audiometer
Block diagram of Audiometer
Diagnostic Audiometer
Needed for advanced testing, other than basic hearing screenings.
A diagnostic or clinical audiometer for testing pure tones as well as speech
testing will also include:
Presentation Indicator
Function Indicator
Microphone
Monitor
Masking Control
CD Player (or tape player)
VU Meter
Air Conduction Output
Tested using supra-aural headphones or insert earphones
Earphones are color coded
Red = Right Ear
Blue = Left Ear
Insert earphones are recommended when possible
Bone Conduction Output
Tested using a vibrator located inside of a plastic shell
Placed against the skull at either the forehead or mastoid process
Sound Field Output
Used to test speech or pure tone signals using loudspeakers in the sound
booth.
If using a pure tone stimulus a warble tone must be used
When using the speaker output, the signal is fed to an auxiliary amplifier
that creates the additional power necessary to drive the loudspeaker.
Measurement of Sound in the Environment
Calibration of Audiometers
Calibration with Sound-Level Meter
Calibration
Direction of the Correction
ComD 3700 Course Notes-Lesson 5
4/19/11 11:08 PM
Lesson 5
Pure Tone Audiometry I
PowerPoint Overview:
Factors in Pure Tone Audiometry:
Test Equipment
Test Environment
The Patient
The Clinician
The Test Procedure
Test Equipment:
Pure Tone Audiometer
Audiometer Limits:
Lower Intensity Limits
0 dB HL to -10 dB HL
Higher Intensity Limits
(see chart)
Output Limits are lower than Air Conduction Output Limits
Reason:
• More power needed to drive BC oscillator
• When BC is driven at high intensity levels, harmonic distortion can
result
• Tactile response can occur
Test Environment:
Ambient room noise may be attenuated 3 ways:
Earphone enclosures
Receiver Inserts
Sound treated chambers
Sound Isolated Chamber:
Rooms are sound treats, not soundproof
One-Room or Two-Room
The Patient:
Patients vary in age, intelligence, education, motivation and willingness to
cooperate
Patient response is required:
• Raise hand
• Raise finger
• Signal button
• Verbal response
The Clinician:
Need be properly trained
Patient position during testing
Proper instruction must be given to patient
Instructing the patient:
Instruct the patient prior to putting on the headphones or through the
microphone
Whenever you are about to do anything, carefully explain to the patient:
• What you are going to do
• What you want them to do, or how you want them to respond
Do not over instruct the client
Remove glasses, hearing instrument and large earrings
Place earphone-make sure tragus is not pushed inward
Start testing with the better ear first
Earphones
Earphone Placement
Bone Oscillator Placement
Threshold
In audiometry, the level at which a stimulus, such as a pure tone, which is
barely perceptible. Usually clinical criteria demand that the level be just high
enough for the subject to be aware of the sound at least 50 percent of the
time it is presented. (Martin, Introduction to Audiology, 2006)
Lowest point where the tone is heard 50% of the time
Audiogram
Frequency:
Vertical Lines
Y Axis
Ordinate
Intensity:
Horizontal Lines
X axis
Abscissa
Audiometric Worksheet
Audiogram Symbols
Placement of Symbols
Pure Tone Average:
The average threshold levels for each ear at 500, 1000 and 2000 Hz
Also known at PTA
Degree of Hearing Loss
Normal Hearing 0-15 dB
Slight Loss 16-25 dB
Mild Hearing Loss 26-40 dB
Moderate Loss 41-55 dB
Moderately Severe Loss 56-70 dB
Severe Hearing Loss 71-90 dB
Profound Hearing Loss >90 dB
Determining Associations:
Test Results
Anatomy
Disorders
Textbook Chapter 4 Overview: (**Use this for Lesson 5 and 6**)
Learning Objectives
Assuming access to an audiometer in good working condition and the
opportunity for supervised experience, upon completion of this chapter, the
reader should be able to:
Describe the fundamentals underlying pure-tone audiometry and the
components of a reliable audiogram.
Demonstrate how different pure-tone tests are performed.
Interpret several pure-tone tests.
Discuss the concepts of cross hearing and when masking signals should be
employed.
Summary
For pure-tone hearing tests to be performed satisfactorily, control is needed
over such factors as background noise levels, equipment calibration, patient
understanding, and clinician expertise. The audiologist must be able to judge
when responses are accurate, and to predict when a sound may have
contralateralized to the ear not being tested. When cross hearing occurs,
proper masking procedures must be instituted to overcome this problem.
Although at times the performance of pure-tone hearing tests is carried out
as an art, it should, in most cases, be approached with a scientific attitude,
using rigid controls.
Outline
The pure-tone audiometer
Test environment
The patient’s role in manual pure-tone audiometry
The clinician’s role in manual pure-tone audiometry
Air-conduction audiometry
Bone-conduction audiometry
Audiogram interpretation
Masking
The audiometric Weber test
Automatic audiometry
Computerized audiometry
Vocabulary
Air-bone gap (ABG)
Air conduction
Audiogram
Audiometer (pure-tone)
Audiometric Weber test
Békésy audiometry
Bone conduction
Calibration
Central masking
Computerized audiometry
Critical band
Inertial bone conduction
Initial masking (IM)
Interaural attenuation (IA)
Masking
Maximum masking
Occlusion effect (OE)
Osseotympanic bone conduction
Overmasking (OM)
Plateau
Pure-tone average (PTA)
Tactile responses
Cross-hearing
Distortional bone conduction
Effective masking (EM)
Electronic voltmeter
Threshold
Undermasking
White noise
ComD 3700 Course Notes-Lesson 6
4/19/11 11:08 PM
Lesson 6
Pure Tone Audiometry II
PowerPoint Overview:
Factors in Pure Tone Audiometry:
Test Equipment
Test Environment
The Patient
The Clinician
The Test Procedure
•
•
•
Air Conduction Audiometry
Bone Conduction Audiometry
Audiogram Interpretation
Procedures for Air Conduction Testing
Carhart-Jerger (1959)
• Also known as the ascending method
• This procedure is used by most audiologists
ASHA Guidelines for manual pure-tone threshold audiometry (2005)
• These guidelines present a recommended set of procedures based
on existing practice and research findings. Their intention is not to
mandate a single way of accomplishing a clinical process, but to
suggest standard procedures that in the final analysis should
benefit the persons we serve.
Threshold Measurement Procedure
The basic procedure for threshold determination consists of:
• familiarization with the test signal
• threshold measurement
The procedure is the same regardless of frequency, output transducer, or
ear under test
Audiologists are encouraged to establish standard procedures and best
practices
Familiarization
The purpose of familiarization is to assure the clinician that the patient
understands and can perform the response task.
The patient should be familiarized with the task before threshold
determination by presenting a signal of sufficient intensity to evoke a clear
response.
The following method is most commonly used:
• 1000 Hz tone is presented at a 30 dB hearing level (HL). If patient
responds, begin threshold measurement. If no response occurs,
present the tone at 50 dB HL and at successive additional
increments of 10 dB until a response is obtained.
Threshold Search
Tone
• Pure-tone stimuli of 1 to 2 seconds' duration
Interval between tones.
• Varied but not shorter than the test tone
Level of first presentation
• Should be below the expected threshold
Levels of succeeding presentations
• The level of each succeeding presentation is determined by the
preceding response. After each failure to respond to a signal, the
level is increased in 5-dB steps until the first response occurs. After
the response, the intensity is decreased 10 dB, and another
ascending series is begun
Method:
1. The tone is presented 10 dB below where the patient responded during
familiarization
2. The level of the tone is raised in 5 dB steps until the patient responds
3. The tone is then decreased by 10 dB and presented again
4. The level of the tone is then raised 5 dB until the patient responds
5. Steps 2 and 3 are repeated until patient responds at the same frequency
2 out of 3 times
Threshold of hearing
Lowest decibel hearing level at which responses occur in at least one half of
a series of ascending trials. The minimum number of responses needed to
determine the threshold of hearing is 2 responses out of 3 presentations at a
single level (ANSI, 2004 and ASHA 2005)
Rules to Remember
If patient does not respond, increase stimulus by 5 dB. If the patient
response is Yes, decrease stimulus by 10 dB
Threshold Search
Frequency
Diagnostic technique (ASHA, 2005)
Threshold assessment should be made at:
• 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz
If a low-frequency hearing loss exists the hearing threshold at 125 Hz should
also be measured
When a difference of 20 dB or more exists between the threshold values at
any two adjacent octave frequencies from 500 to 2000 Hz, test interoctaves
Order
If the information is available, the better ear should be tested first
The initial test frequency should be 1000 Hz
Follow in order, 2000, 3000, 4000, 6000, and 8000 Hz
Retest 1000 Hz
Test 500, 250, and 125 Hz
Why go back to 1000 Hz?
• Most easily heard frequency
• Best test-retest reliability
•
Procedures for Bone Conduction Testing
Procedures for find BC threshold are essentially identical to finding AC
thresholds
Performed in the similar order of 1000, 2000, 4000, retest at 1000, 500 and
250 Hz
Can start BC testing in either ear-the vibration of the skull will result in
approximately equal stimulation of both cochleas
The tone will be heard by the cochlea with the better hearing
Contributors to Bone Conduction Hearing
Distortional Bone Conduction
• Role of inner ear
• Primary contributor to BC thresholds
Inertial Bone Conduction
• Role of middle ear
• Lag of middle ear bones
Osseotympanic Bone Conduction
• Role of outer ear
• Osseous-bone
•
Tympanic-tympanic membrane
Occlusion Effect
Occurs when earphones are used during BC testing
Impacts patients with normal hearing or sensorineural hearing loss
Occlusion Effect Levels
Audiogram Interpretation
Audiogram results are interpreted in terms of:
Amount of hearing loss by air conduction
• Tests the entire auditory pathway
Amount of hearing loss by bone conduction
• Tests the inner ear and auditory nerve only
Relationship between air conduction and bone conduction results
• Difference between the AC and BC results implies a problem with
the conductive system
Known as an air-bone gap (ABG)
• AC – BC = ABG
• Whole ear hearing loss minus sensorineural part of the hearing loss
= conductive hearing loss
Normal Hearing
No hearing loss by either air conduction or bone conduction
Conductive Hearing Loss
Mild Conductive Hearing Loss in the Right Ear
Bilateral Mild Conductive Hearing Loss
Sensorineural Hearing Loss
Bilateral Mild to Moderate Sensorineural Hearing Loss
Bilateral Sloping Mild to Profound Sensorineural Hearing Loss
Bilateral Mild Precipitously Sloping to Profound Hearing Loss
Bilateral Profound Sensorineural Hearing Loss
Mixed Hearing Loss
Bilateral mild to severe mixed hearing loss
ComD 3700 Course Notes-Lesson 7
4/19/11 11:08 PM
Lesson 7
Masking I
PowerPoint Overview:
Masking
Masking occurs when an unwanted sound causes a wanted sound to be
inaudible.
Masking is required to keep a better ear busy while testing a poorer ear. The
poorer ear receives the tone while the better ear hears a controlled masking
noise
Test Ear & Non-Test Ear
Cross Hearing
The reception of a sound signal during a hearing test at the ear opposite the
ear being tested
It is possible during audiometric testing for the stimulus presentation
(sound) to travel from the poorer ear to the better ear
Can occur when testing by air conduction and by bone conduction
Cross Hearing-Sample Patient
Expected Audiogram
Audiogram without Masking
Audiogram with Masking
Interaural Attenuation
As sound travels from one side of the head to the other, a certain amount of
energy is lost in transmission
This loss is called interaural attenuation (IA)
IA varies with frequency (Hz) and individual patients
IA for Air Conduction has been established as 40 dB when using supra aural
headphones
IA for Air Conduction has been established as 70 dB when using insert
headphones
IA for Bone Conduction has been established as 0 dB
Cross Hearing in Air Conduction Testing
In AC testing, cross hearing can be expected when:
AC (TE) –IA ≥ BC (NTE)
Cross Hearing in Bone Conduction
In BC testing, cross hearing can be expected when:
ABG (TE) > 10 dB
Central Masking
It has be shown that a small shift is seen in the threshold of a pure tone
when a masking noise is introduced into the opposite ear.
This increased shift averages about 5 dB
It is believed that the elevation of threshold is produced by inhibition that is
sent down from the auditory centers in the brain and has, therefore, been
called central masking. (Martin, Introduction to Aud., 9th Ed.)
Textbook Chapter 4 Overview: (**Use this for Lesson 7 and 8**)
Learning Objectives
Assuming access to an audiometer in good working condition and the
opportunity for supervised experience, upon completion of this chapter, the
reader should be able to:
Discuss the concepts of cross hearing and when masking signals should be
employed.
Summary
For pure-tone hearing tests to be performed satisfactorily, control is needed
over such factors as background noise levels, equipment calibration, patient
understanding, and clinician expertise. The audiologist must be able to judge
when responses are accurate, and to predict when a sound may have
contralateralized to the ear not being tested. When cross hearing occurs,
proper masking procedures must be instituted to overcome this problem.
Although at times the performance of pure-tone hearing tests is carried out
as an art, it should, in most cases, be approached with a scientific attitude,
using rigid controls.
Outline
Masking
The audiometric Weber test
Automatic audiometry
Computerized audiometry
Vocabulary
Air-bone gap (ABG)
Air conduction
Audiogram
Audiometer (pure-tone)
Audiometric Weber test
Békésy audiometry
Bone conduction
Calibration
Central masking
Computerized audiometry
Critical band
Cross-hearing
Distortional bone conduction
Effective masking (EM)
Electronic voltmeter
Inertial bone conduction
Initial masking (IM)
Interaural attenuation (IA)
Masking
Maximum masking
Occlusion effect (OE)
Osseotympanic bone conduction
Overmasking (OM)
Plateau
Pure-tone average (PTA)
Tactile responses
Threshold
Undermasking
White noise
ComD 3700 Course Notes-Lesson 8
4/19/11 11:08 PM
Lesson 8
Masking II
PowerPoint Overview:
Patient Instructions
Explain what will happen and how they are to respond
May help to explain optometrist analogy
Example:
You will hear some tones again. Every time you hear a tone, push the
button/raise your hand. You will hear some noise in the LEFT/RIGHT ear
(describe it as static or running water and tell the patient which ear it will be
heard in.) Ignore the noise, and listen for the tone. It doesn’t matter which
ear you hear the tone in, go ahead and respond. Do you have any
questions?
White Noise
Narrow Band Noise (NBN)
Masking Noise
The appropriate type of masking depends of the signal being masked
If the signal has a wide spectrum (Speech or Clicks) then the masking noise
must also have a wide spectrum
Other masking noises for speech tests include:
• Pink Noise
• Speech Shaped Noise
• Multitalker babble
Masking Terminology
Effective Masking (EM) eliminates cross-over from occurring. EM
determines how much noise is appropriate to ‘cover up’ or ‘keep busy’ the
better ear or NTE from taking part in the test
Undermasking occurs when the masking noise presented to the NTE is not
loud enough to eliminate crossover or IA
Overmasking is the condition when the noise presented to the NTE is
intense enough to cross over to the TE and mask it
Masking Methods for Air Conduction
Shotgun Method
Minimum Noise Method
Maximum Noise Method
Plateau Method
Step Masking Method
Plateau Method
A gradual increase in masking in the NTE to find a plateau (Hood J. (1960)
What is plateau? A range of masking levels in which there is no increase in
threshold of the TE (using 5 or 10 dB steps at a time)
When an adequate level of masking has been reached, there are generally
several successive levels of masking that yield the same PT threshold in the
TE (produces no threshold shift in the TE)
Most audiologists uses 3 consecutive masked levels (5 or 10 dB steps) with
the same response to be a threshold
If you use 10 dB steps, some times only 2 consecutive masked levels are
taken to avoid overmasking–but if you use 5 dB steps, you have to establish
3 consecutive masked levels
Plateau Method Procedure for Air Conduction
Obtain and record the AC threshold of the TE unmasked
Compare the AC threshold of the TE with AC and BC thresholds of NTE to
determine if masking is needed
• Is there a difference of 40dB or greater using supra aural
headphones or 70 dB or greater using insert earphones?
Select the initial amount of masking (IM) using narrow band noise on the
audiometer for the NTE
IM = AC NTE+ 10 dB EML
• Note: Some audiologists use 5 dB or 15 dB effective masking level
•
(EML)
For example: if AC NTE =10 dB, then present 20 (10 +10 EML) dB
of NBN to the NTE
Reestablish threshold in the TE with this initial amount of masking in the NTE
Each time the patient responds to the PT signal presented to the TE,
increase masking noise in the NTE by 10 dB
Each time the patient does not respond to the PT signal in the TE, increase
the tone in the TE in 5 dB steps until the patient responds again
Continue the procedure until the masking noise can be increased over a 30
dB interval (3 consecutive 10 dB steps) without producing a shift in the
threshold level of the TE
This is the “Plateau” and the AC pure tone intensity level you reached is the
actual threshold of the TE J
Masking Methods for Bone Conduction
The test ear, with the bone vibrator on the mastoid process, must not be
occluded in any way with the earphone
Plateau Method for Bone Conduction
Obtain and record the BC threshold of the TE unmasked and unoccluded
Compare the AC thresholds with the BC thresholds (ABG) to determine if
masking is needed
• Is there a difference of 10 dB or more?
Select the initial amount of masking (IM) for the NTE using NBN
• IM = AC NTE+ 10 dB EML + OE
• OE= Add an additional 15 dB at 250 Hz and 500 Hz and 10 dB at
1000 Hz
Reestablish threshold in the TE with this initial amount of masking in the NTE
Each time the patient responds to the PT signal presented to the TE,
increase masking noise in the NTE by 10 dB
Each time the pt. does not respond to the PT signal in the TE, increase the
tone in the TE in 5 dB steps until the patient responds again
Continue the procedure until the masking noise can be increased over a 30
dB interval (3 consecutive 10 dB steps) without producing a shift in the
threshold level of the TE
This is the “Plateau” and the BC pure tone intensity level you reached is the
actual threshold of the TE J
Plotting Masked Thresholds
Air conduction:
Right Ear unmasked: O
Right Ear Masked : Δ
Left Ear unmasked: X
Left Ear Masked:
Bone conduction:
Right Ear unmasked: <
Right Ear Masked: [
Left Ear unmasked: >
Left Ear masked: ]
Audiogram Interpretation
Rule to Remember
It is better to mask and find out that it was not required
Test results obtained without masking when there is a need for masking,
result in improper test results
Masking is time consuming and adds several steps to the test procedure, so
it is important to understand the rules of when to mask
ComD 3700 Course Notes-Lesson 9
4/19/11 11:08 PM
Lesson 9
Speech Audiometry I
PowerPoint Overview:
Speech Audiometry
Hearing and understanding speech is the greatest complaint of hearing
impaired patients
Hearing loss depicted by the pure tone audiogram cannot reflect the degree
of handicap in speech communication
It is logical that tests of hearing function should be performed with speech
as the stimuli
SLP’s use the speech results in therapy planning and counseling.
Factors in Speech Audiometry
Test Equipment
Test Environment
The Patient
The Clinician
The Test Procedure
Test Equipment
Test Environment
Monitored live voice
• 2 Room Suite
Prerecorded Materials
• 1 Room Suite
• 2 Room Suite
Advantages of using prerecorded materials include the absence of
inconsistency between examiners voices and mannerisms
However, most clinicians use monitored live voice (MLV)
• flexibility
•
saves time
The Patient
Spoken Response
• Advantages
o Faster
o Rapport maintained between clinician and client
• Disadvantages
o Client may have poor or unintelligible speech
Written Response
• Advantages
o Patient’s poor speech not a factor
o Provides a permanent record
• Disadvantages
o Slows down the testing procedure
o Takes time to score
The Clinician
Needs be properly trained
Proper instruction must be given to patient
Patient position during testing
Test Procedure
Speech Detection Threshold (SDT or SAT)
Speech Recognition Threshold (SRT)
Most Comfortable Loudness Level (MCL)
Uncomfortable Loudness Level (UCL)
Word Recognition Score (WRS)
Speech Detection Threshold
Speech Awareness Threshold (SAT) is a commonly used synonym for SDT
Defined as the lowest level in dB that a person can just detect the presence
of speech and identify it as speech 50% of the time
The stimulus is usually sentences or connected speech (cold running speech)
SDT is helpful when working with uncooperative children
This is not a popular measure because of a lack of relevant information
Speech Recognition Threshold
Defined as the lowest level in dB that a person can identify correctly the
speech stimuli 50% of the time
Formerly known as Speech Reception Threshold
Hudgins et.al. (1947) investigated words for use in SRT testing and
suggested the words should satisfy four criteria:
• Familiarity
• Phonetic dissimilarity
• Normal sampling of English speech
• Homogeneity with respect to audibility
36 two syllable words have been shown to meet the criteria very well and
are used by most individuals today
These speech materials are called spondaic words or spondees
A spondee word is a two syllable word spoken with equal stress on each
syllable
Spondees do not occur in spoken english
Examples of spondee words:
Airplane
Toothbrush
Hotdog
Sidewalk
Baseball
Pancake
Cowboy
Armchair
Eardrum
SRT Testing Procedures:
ASHA (1988) Method
Martin and Dowdy (1986) Procedure
Similar to the ASHA (1978) method for determining pure tone thresholds
Review procedure on page 132 of textbook
Martin suggests his procedure because:
• It requires no knowledge of other test results
• It involves the use of 5 dB steps – the same as pure tone
Review procedure on page 132 of textbook (10th Edition)
Carrier Phrase, “Say the word”
Patient Instructions
“You are going to hear a person ask you to say a series of words, like
‘baseball’ and ‘schoolboy’. I’d like you to repeat each word you are asked to
say. I’m going to turn the words quieter and quieter, until you can’t hear
them anymore. I want to find out how quietly you can hear speech. Don’t be
afraid to guess. Do you understand?”
SRT results are used:
As a basis for setting a level for Word Recognition (WRS) testing
As a check on pure tone results
SRT can be predicted from the PTA
• SRT = PTA plus or minus 5 dB
To categorize hearing loss
To help with judgments as to need for amplification
In hearing aid evaluations to determine the correct amount of gain
Textbook Chapter 5 Overview: (**Use this for Lesson 9 and 10**)
Learning Objectives
Chapter 4 introduced the concept of pure-tone audiometry and described its
administration and interpretation. This chapter acquaints the reader with
speech audiometry and some of its ramifications. The new vocabulary in this
chapter is indispensable for understanding the concepts that follow in this
book. Upon completion of this chapter the beginning student should:
Have a fundamental knowledge of the measures obtained with speech
audiometry such as threshold for speech, most comfortable and
uncomfortable loudness levels, and word-recognition ability.
Be able to interpret speech audiometric results; relate them to pure-tone
threshold tests; and after some supervised practice with an audiometer,
actually perform the tests described in this chapter and correctly apply
masking when indicated.
Understand the implications of speech audiometric tests to speech-language
therapy planning and goal setting.
Summary
Speech audiometry includes measurement of a patient’s thresholds for
speech—speech-recognition threshold (SRT) and speech-detection threshold
(SDT)—as well as the most comfortable loudness level (MCL), uncomfortable
loudness level (UCL [or loudness discomfort level LDL]), range of
comfortable loudness (RCL [or dynamic range, DR]), and speech-recognition
score (SRS). Measurements may be made either monaurally or binaurally
under earphones, through a bone-conduction vibrator or in the sound field
through loudspeakers. Materials for speech audiometry may include
connected speech, two-syllable (spondaic) words, monosyllabic words, or
sentences. The materials may be presented by means of a tape recorder, CD
player, or microphone (using monitored-live voice). At times the sensitivity
of the nontest ear by bone conduction is such that it may inadvertently
participate in a test under earphones. When cross hearing is a danger, a
masking noise must be presented to the nontest ear to eliminate its
participation in the test.
Measurements using speech audiometry augment the findings of pure-tone
tests and help to determine the extent of a patient’s hearing loss, loudness
tolerance, and speech recognition. The knowledge gained from the use of
speech audiometry is helpful in the diagnosis of the site of lesion in the
auditory system, as well as in audiological treatment.
Outline
The diagnostic audiometer
Test environment
The patient’s role in speech audiometry
The clinician’s role in speech audiometry
Speech-threshold testing
Masking for SRT
Bone-conduction SRT
Most comfortable loudness level
Uncomfortable loudness level
Range of comfortable loudness
Speech-recognition testing
Computerized speech audiometry
Vocabulary
Binaural
California Consonant Test
Carrier phrase
Cold running speech
Connected speech
Connected Speech Test (CST)
Consonant-nucleus-consonant (CNC)
Performance-intensity function
Picture Identification Task (PIT)
Range of comfortable loudness (RCL)
Signal-to-noise ratio (SNR)
Speech-detection threshold (SDT)
Word-recognition score (WRS)
Speech Perception in Noise (SPIN)
Dynamic range (DR)
Loudness discomfort level
Monaural
Monitored live voice (MLV)
Most comfortable loudness (MCL)
NUCHIPS
PB Max
PB word list
Speech-recognition threshold (SRT)
Spondaic word
Spondee
Synthetic sentence identification
Threshold of discomfort (TD)
Tolerance level
Uncomfortable loudness level (UCL)
WIPI
ComD 3700 Course Notes-Lesson 10
4/19/11 11:08 PM
Lesson 10
Speech Audiometry II
Factors in Speech Audiometry
Test Equipment
Test Environment
The Patient
The Clinician
The Test Procedure
Test Procedure
Speech Detection Threshold (SDT or SAT)
Speech Recognition Threshold (SRT or ST)
Most Comfortable Loudness Level (MCL)
Uncomfortable Loudness Level (UCL)
Word Recognition Score (WRS) or Speech Recognition Testing
Most Comfortable Loudness Level
Purpose: to determine the best level for the patient to hear and understand
speech
Usually 40 to 55 dB HL in normal hearing patients
Stimulus: cold running speech
A bracketing method is used to find MCL
Can be found monaurally, binaurally or in sound field
Most often used in the evaluation of hearing aids
MCL Patient Instructions
“Now you are going to hear continuous speech. You do not have to repeat
any of the words. I want to find the most comfortable level for you to listen.
I will increase the volume slowly, so you can listen at different levels. You
can help me by pointing your thumb up if you want it louder, or down if you
want it quieter. Please let me know when we find the volume you prefer. Do
you understand?”
Uncomfortable Loudness Level
Purpose: to determine the point where no further loudness will be accepted
by the patient
Usually 100 to 110 dB HL in normal hearing patients
Stimulus: cold running speech
Most often used in the evaluation of hearing aids
Hearing losses DO NOT necessarily extend the UCL
Also known as:
TD: Threshold of Discomfort
Tolerance Level
LDL: Loudness Discomfort Level
Uncomfortable Loudness Level
UCL Patient Instructions
“Now I want to find a level where sound starts to bother you, not where it is
just a little too loud. I want to find where it is uncomfortable for you, but not
painful. I don’t want you to hold you ears in pain. Please raise you hand or
stay ‘stop’ whenever the sound starts to bother you to the point where you
couldn’t listen to it or when exceeding the loudness level would be
intolerable.
Dynamic Range
Dynamic Range (DR) can also be known as Range of Comfortable Loudness
(RCL)
Calculated by subtracting the SRT from the UCL
People with normal hearing have a DR of 100 dB or more
People with a sensorineural hearing loss may have a DR of 35 dB or less
Speech Recognition Testing
Also referred to as:
Word recognition testing
Word discrimination testing
Speech discrimination testing
The measurement of speech discrimination is referred to as:
Speech recognition score (SRS)
Word recognition score (WRS)
Speech discrimination score
Speech Recognition Testing Purpose:
To determine the extent of the speech-recognition difficulty
To aid in diagnosis of the site of the disorder in the auditory system
To assists in the determination of the need for and proper selection of
hearing instruments
To help the clinician make a prognosis for the outcome of treatment efforts
Speech Recognition Testing Procedure
Phonetically Balanced Word Lists
• Central Institute for the Deaf (CID) Auditory Test W-22
o CID-W-22
• Northwestern University Test No. 6
o NU-6
50 word list is recommended
No familiarization is needed
Carrier phrase is used
Say the word
Prerecorded test materials are preferred
Test Presentation Level
Standard procedure: 40 dB SL above the SRT
If too loud present at 30 dB SL above the SRT
If still too loud-present at MCL
Textbook recommends testing at a minimum of 2 levels
First level: 5 to 10 dB above the patient’s MCL
Second level: higher intensity (90 dB)
Testing at conversational levels (45-50 dB HL)
Useful for counseling purposes to demonstrate difficulties experienced and
the potential benefits from amplification
Speech Recognition Testing Patient Instructions
“You are going to hear a series of words. Please repeat each of the words
you are asked to say. If you have difficulty understanding the words, it helps
me if you guess. I have a better idea what part of the word was difficult for
you. If the volume is not comfortable for you, or you would like the words
louder or quieter, please let me know. Do you understand?”
Recording Speech Recognition Testing
Results are recorded in terms of the % of correctly identified words. Each
correct response is worth 2% if using a 50 word list and 4% if using a 25
word list.
The list used and the level at which the testing was performed is also noted
on the audiogram.
Speech Recognition Testing Results
Results suggest the approximate degree of difficulty the individual will
experience understanding speech for each ear in a quiet listening condition.
General word-recognition ability:
92-100% Excellent
82-90%
Good
72-80%
Fair
52-70%
Poor
22-50%
Very Poor
0-20%
Extremely Poor
Expected WRS based on degree of hearing loss:
Normal hearing - the score should be 90% or better
Cochlear disorders - the score is usually consistent with the degree of
hearing loss; the greater the loss, the poorer the WRS.
Retrocochlear disorders - the score is usually considerably poorer than
expected based on the degree of hearing loss.
Performance Intensity Function
Summary of Speech Audiometry
Speech tests verify the audiogram
Review audiograms and speech results on pages 157-159 of your textbook
Summary of tests used in speech audiometry on page 160
ComD 3700 Course Notes-Lesson 11
4/19/11 11:08 PM
Lesson 11
Immittance Testing
Audiometric Testing Review
Acoustic Immittance Introduction
A way of assessing the manner in which energy flows through the outer and
middle ear into the cochlea
Purpose is to evaluate middle ear status and neural pathways
Information gained helps us:
• Understand how middle ear is functioning
• Differentiate cochlear from retrocochlear pathology
• Estimate sensitivity
• Use in cross-check with pure tone results
• Know when a medical referral is needed
Advantages of Immittance
• Non-invasive
• Non-behavioral
Scope of Practice
Speech-language pathologists provide clinical services that include the
following:
Screening individuals for hearing loss or middle ear pathology using
conventional pure-tone air conduction methods (including otoscopic
inspection), otoacoustic emissions screening, and/or screening
tympanometry
Audiologists will perform immittance testing as part of a diagnostic
evaluation
Greater detail will be provided during your graduate studies. This course is
designed to give you an overview in preparation for advanced learning.
Acoustic Immittance Definitions
Immittance is an all encompassing term to describe measurements made of
tympanic membrane (TM) impedance, admittance or compliance
Acoustic impedance (Z)
• Opposition to the flow of acoustic energy to the middle ear
• Measured in ohms
Acoustic admittance (Y)
• Acoustic energy passed by the TM into the middle ear
• Expressed in acoustic millimhos (mmhos)
Compliance
• Related to the dimensions of an enclosed volume of air
• Expressed in a scale of different units of measurement
• Cubic centimeters or milliliters
Acoustic Immittance Tests
Basic Immittance Measures include:
•
•
•
•
Static Compliance
Tympanometry
Acoustic Reflex Testing
o Thresholds
o Decay
Eustachian Tube Function
Anatomy of Ear
Middle Ear Anatomy
Basic Physics of Sound
Sound Pressure Level
Immittance Equipment
Major components for immittance measurements
• Probe with three tubes
o Loudspeaker to emit a pure tone
o Microphone to pick up sound in the ear canal
o Air pump to change pressure in the ear canal
• Contralateral earphone
o Acoustic reflex testing
Air Pressure
Air pressure causes the TM to move
Positive pressure: pushes TM away from us
Negative pressure: pulls TM toward us
Air Pump Calibration
• Milliliters (ml)
• Millimeters of water (mm H2O or mmho)
• Dekapascals (daPa)
Pressure Amount
• + 200 ml to – 200 ml
Measurements are made in dB SPL
Immittance Equipment
Preparing the Patient
Seat the patient facing the immittance meter
Do an otoscopic examination.
Give instructions to the patient
Select a probe tip to fit the ear canal tightly
Place a probe tip on the end of the probe and insert it into ear canal; you
want it to stay in place without holding it
Run the immittance test
Patient Instructions
This is a test to see how well the ear drum is moving. I’m going to put a soft
plug into your ear canal so that it will fit tightly. We need to get an air-tight
seal. You will hear a tone, which may vary in loudness. You will feel changes
in air pressure. It will feel similar to when your ears don’t pop when going in
an airplane. Try to avoid talking, swallowing or yawning while the test is
running. You just need to sit quietly without moving; the test is automatic.
Textbook Chapter 6 Overview: (**Use this for Lesson 11-13**)
Learning Objectives
The purpose of this chapter is to discuss some of the electroacoustical and
electrophysiological procedures that have been developed to serve both as
indices of hearing sensitivity and as indications of the site of a lesion in the
auditory system. These tests do not require behavioral responses from
patients. Upon completion of this chapter, the reader should be able to:
Discuss the purpose of acoustic immittance testing and, following supervised
practice, perform tympanometry and acoustic reflex testing on a fellow
student or friend.
Describe the expected immittance results for several different ear
pathologies.
Define the differences among spontaneous, transient-evoked and distortionproduct otoacoustic emissions.
Describe how evoked auditory potentials are measured and what these
measures can reveal about hearing function and the site of lesion within the
auditory system.
Summary
Acoustic immittance measurements and tympanometry give remarkably
reliable information regarding the function of the middle ear, and acoustic
reflex measurements have become essential in diagnostic audiometry.
Auditory brainstem response (ABR) audiometry has become an important
part of the site-of-lesion test battery, and some of the other evoked
potential techniques are becoming more valuable as they are improved.
Otoacoustic emissions have added significantly to the battery of tests for site
of lesion and it is expected that refinement of the present techniques and
new experimental findings will add greatly to the practical use of this
procedure.
Outline
Acoustic immittance
Acoustic reflex
Otoacoustic emissions (OAE)
Auditory evoked potentials
Vocabulary
Acoustic impedance
Intra-aural muscle reflex
Acoustic reflex arc
Acoustic reflex decay
Acoustic reflex threshold (ART)
Intraoperative monitoring
Late evoked response (LER)
Latency
Active electrode
Auditory brainstem response (ABR)
Auditory event-related potential
(ERP)
Auditory evoked potentials (AEP)
Auditory middle latency response
(AMLR)
Compliance
Distortion product otoacoustic
emissions
Electrocochleography (ECoG)
Loudness recruitment
Mismatch negativity (MMN)
Reactance
Reference electrode
Reflex activating stimulus (RAS)
Short Increment Sensitivity Index
(SISI)
Spontaneous otoacoustic emissions
(SOAE)
Stapedius muscle
Static acoustic compliance
Electroencephalograph (EEG)
Equivalent volume
Evoked otoacoustic emission (EOAE)
Gradient
Ground electrode
Immittance
Tensor tympani muscle
Tone decay
Transient-evoked otoacoustic
emission
Tympanogram
Tympanometry
ComD 3700 Course Notes-Lesson 12
4/19/11 11:08 PM
Lesson 12
Tympanometry
Acoustic Immittance Tests
Basic Immittance Measures include:
• Static Compliance
• Tympanometry
• Acoustic Reflex Testing
o Thresholds
o Decay
• Eustachian Tube Function
Immittance Equipment
Tympanometry
Provides information on the condition of the middle ear structures
Aim: To determine the pressure at which the TM is maximally compliant and
the amount of compliance at that point
Measuring the compliance of the tympanic membrane as a function of the
pressure in the ear canal
Membrane vibrates most efficiently when the pressure on both sides is equal
Conducted using low-frequency probe tone of 220 or 226 Hz
Tympanogram Elements
A-Ear Canal Volume
B-Peak Compliance
C-Ear Indicator
D-Pressure Peak
E-Pressure Tracing
F-+200 daPa pressure
G-0 daPa pressure
H-Unit of measure
I- -400 daPa pressure
J-Gradient
Static Acoustic Compliance
Sometimes referred to as Static Acoustic Admittance or Static Immittance
Determines the degree of stiffness of the tympanic membrane and ossicular
chain
Measures the mobility of the TM in response to a given pressure in the
external canal
Recorded as the height of the tympanogram measured at the plane of the
TM
Static Acoustic Compliance Procedures
Positive pressure is increased to +200 daPa using pressure pump. Measure
equivalent volume (C1)
Tympanic Membrane is tight
Decrease pressure until the TM is maximally compliant or until outer ear
pressure is at 0 daPa (C2)
Tympanic Membrane is loose
Static Compliance = C2 – C1
Static Acoustic Compliance Results
Normal values
Children = 0.25 to 1.05 ml
Adults = 0.30 to 1.70 ml
Low Value: stiffness of TM and/or ossicular chain
Otosclerosis
Fluid
Tympanosclerosis
High Value: interruption of ossicular chain
Disarticulation
Flaccid TM
Results are extremely variable. By itself, static compliance is the least
helpful of all immittance tests because of this variability.
Results are not considered abnormal unless one of the extremes is clearly
exceeded.
The results need to be reviewed in conjunction with the rest of the
immittance testing to determine validity.
Ear Canal Volume
Equivalent Ear Canal Volume (Vec or Vea)
Measure at +200 daPa
Provides measure of volume of external ear canal
Volume norms based on age
Normal Ranges:
• Adult=.6 to 1.5 mL or cc
• Child=.4 to 1.0 mL or cc
• Infant=.3 to .9 mL or cc
Volumes greater than 2.0(adult) or .9 (child) suggest:
• Perforation
•
Patent PE tube
Middle Ear Pressure
MEP, TTP, Peak Pressure or Pressure Peak
Pressure at which the peak is located
Measured on the X-axis
Normal Range:
• -150 to +100 daPa
Pressure below -100 daPa suggests:
• Congestion
• Serous Otitis Media with air pockets
• Referral needed
Gradient
Tympanometric Width
Steepness
Low value
• Steep
• Tall
• Greater Peak
High value
• Broad
• Short
• Lower Peak
Normal Range
•
•
Results
•
Adult=51-114 daPa
Child=80-159 daPa
higher than 200 daPa consistent with:
Middle ear fluid
Tympanometric Measurements
Tympanogram Shapes
Tympanogram Types (Jerger)
Type A Tympanogram
Normal shape
Intact eardrum
Functioning Eustachian tube
Normal muscles and ligaments
Type As Tympanogram
S = Shallow or Stiff
Normal pressure
Low Compliance
Ossicular Fixation
Tympanosclerosis
Type AD Tympanogram
D = Deep or Disarticulated or Discontinuous
Normal Pressure
High Compliance
Monomeric TM
Ossicular Discontinuity
Type B Tympanogram
TM does not move due to:
•
•
•
Probe Placement
Perforation
Fluid
• Disease
No pressure peak
Refer to ECV
Type C Tympanogram
Negative Pressure
Peak is -150 to -200
Normal compliance
Eustachian tube dysfunction
Developing or resolving otitis media
Tympanogram Types Summary
Immittance Screening Guideline
Ear Canal Volume measurement (ECV)
• PASS - Open PE tube ð Volume larger than expected for age norms
• FAIL - Blockage or probe against canal wall ð Volume smaller than
expected for age norms
Peak Pressure
• PASS - Normal: between -100 to +50 daPa ð air pressure in middle
•
ear similar to atmospheric pressure
PASS - Positive: between +50 to +200 daPa ð air pressure in
•
middle ear greater than atmospheric pressure
FAIL - Negative: below -100 daPa ð air pressure in middle ear less
than atmospheric pressure; common with congestion
Static Compliance
• PASS - .3 to 2.4 normal range
• PASS - Below = minimal compliance
• FAIL - Above = flaccid TM
Gradient
FAIL - 275 daPa abnormal, consistent with fluid in the middle ear
Immittance Referral Guideline
Flat tympanogram with large ECV measurement & no known PE tube
• Medical Referral
Flat tympanogram with normal ECV measurement
Re-screen in 2 weeks
o Same result at 2nd screening
§ Medical Referral
Negative pressure tympanogram
• Re-screen 2 weeks
Fail pure tone any frequency either ear and normal tympanogram
• Re-screen 2 weeks
Fail pure tone any frequency either ear and abnormal tympanogram
• Re-screen in 2 weeks
o Same result at 2nd screening
§ Medical Referral
•
Reference: American Speech-Language-Hearing Association Audiologic
Assessment Panel 1996 (1997). Guidelines for audiologic screening.
Rockville. MD: Author.
Tympanogram Interpretation
Normal Tympanogram
Type A
Normal Mobility
Normal ECV (1.0 cm3)
Normal Compliance (Peak: 0.5 cm3)
Normal Middle-ear Pressure (0 daPa)
Normal Gradient (85 daPa)
Middle Ear Fluid
Type B
No Mobility
Normal ECV (1.0 cm3)
No Compliance (No Peak)
No Middle-ear Pressure
No Gradient
TM Perforation or PE Tube
Type B
No Mobility
Abnormal ECV (3.5 cm3)
No Compliance (No Peak)
No Middle-ear Pressure
No Gradient
Poorly Functioning Eustachian Tube
Type C
Restricted Mobility
Normal ECV (1.0 cm3)
Normal Compliance(Peak: 0.4 cm3)
Abnormal Middle-ear Pressure (-195 daPa)
Borderline wide Gradient (135 daPa)
Scarred TM
Type AD
Hyperflaccid Mobility
Normal ECV (1.2 cm3)
Abnormal Compliance(Peak: 1.8 cm3)
Normal Middle-ear Pressure (-30 daPa)
Borderline Narrow Gradient (50 daPa)
Tympanogram Interpretation
Textbook Chapter 6 Overview: (**Refer to Lesson 11**)
ComD 3700 Course Notes-Lesson 13
4/19/11 11:08 PM
Lesson 13
Acoustic Reflex
Acoustic Immittance Tests
Basic Immittance Measures include:
Static Compliance
Tympanometry
Acoustic Reflex Testing
Thresholds
Decay
Eustachian Tube Function
Acoustic Reflex Testing Equipment
Anatomy of Acoustic Reflex
Acoustic Reflex Definitions
Acoustic Reflex (AR)
• The contraction of one or both of the middle-ear muscles in
response to an intense sound
• Protect the ear
The 2 muscles associated with the middle ear
• Tensor Tympani
• Stapedius
Ipsilateral (Ipsi)
• Stimulus and measurement occur on the same ear
• Tone is presented on the probe side
Contralateral (Contra)
• Stimulus presented to one ear, measurement occurs in the opposite
ear
• Tone is presented on the earphone side
Results are reported by the ear that is stimulated by the signal
Acoustic Reflex Measurement
Acoustic Reflex Pathway
Right Ipsilateral Pathway
Right Contralateral Pathway
Left Ipsilateral Pathway
Left Contralateral Pathway
Acoustic Reflex Threshold (ART)
The lowest level at which an AR can be obtained
Normal acoustic reflex responses occur with a stimulus of 85 to 100 dB SPL
ART are usually found at 500, 1000, 2000 and 4000 Hz
Signal is introduced at 70 dB and then increased by 5dB or decreased by 10
• dB until a threshold is found
Signal should not exceed 115 dB HL
Test results
• Can suggest a site of lesion
• Differentiate cochlear from retrocochlear pathology
• Provide information on possible hearing levels
Reflex Threshold Results
Acoustic Reflex Threshold Results
Acoustic Reflex Threshold Outcomes
Present at Normal SL
• About 85 dB SL
• Normal hearing
Absent
• No response at 115 dB HL
• Hearing loss
o Conductive (probe ear)
o Moderate to severe SNHL
Present at Low SL
• Less than 60 dB SL
Hearing Loss
o Mild to moderate SNHL
o Associated with cochlear site of lesion
Present at High SL (Elevated)
• Greater than 100 dB SL
• Hearing Loss
o Conductive hearing loss (stimulus ear)
o Normal hearing
§ Associated with retrocochlear lesion/VIIIth nerve
damage
•
Acoustic Reflex Results-Normal Hearing
Acoustic Reflex Results-Right Ear Normal Hearing/Left Ear MildModerate SNHL
Acoustic Reflex Threshold Outcomes- Right Ear Normal Hearing/Left
Ear Mild- Moderate SNHL
Present at Normal SL (Right Ear)
• About 85 dB SL
• Normal hearing
Absent
• No response at 115 dB HL
• Hearing loss
o Conductive (probe ear)
o Moderate to severe SNHL
Present at Low SL (Left Ear)
• Less than 60 dB SL
• Hearing Loss
o Mild to moderate SNHL
o Associated with cochlear site of lesion
Present at High SL (Elevated)
• Greater than 100 dB SL
•
Hearing Loss
o Conductive hearing loss (stimulus ear)
o Normal hearing
§
Associated with retrocochlear lesion/VIIIth nerve
damage
Acoustic Reflex Results-Right and Left Severe Cochlear Hearing Loss
Acoustic Reflex Threshold Outcomes
Present at Normal SL
• About 85 dB SL
• Normal hearing
Absent (Right & Left Ear)
• No response at 115 dB HL
•
Present
•
•
Present
•
•
Hearing loss
o Conductive (probe ear)
o Moderate to severe SNHL
at Low SL
Less than 60 dB SL
Hearing Loss
o Mild to moderate SNHL
o Associated with cochlear site of lesion
at High SL (Elevated)
Greater than 100 dB SL
Hearing Loss
o Conductive hearing loss (stimulus ear)
o Normal hearing
§ Associated with retrocochlear lesion/VIIIth nerve
damage
Acoustic Reflex Results-Undetermined
Acoustic Reflex Threshold Outcomes
Present at Normal SL (Right ipsi)
• About 85 dB SL
• Normal hearing
Absent (R contra-probe ear & L ipsi-probe ear)
• No response at 115 dB HL
• Hearing loss
Present
•
•
Present
•
•
o Conductive (probe ear)
o Moderate to severe SNHL
at Low SL
Less than 60 dB SL
Hearing Loss
o Mild to moderate SNHL
o Associated with cochlear site of lesion
at High SL (Elevated) (L contra-stimulus ear)
Greater than 100 dB SL
Hearing Loss
o Conductive hearing loss (stimulus ear)
o Normal hearing
§ Associated with retrocochlear lesion/VIIIth nerve
damage
Acoustic Reflex Results-R Normal Hearing/L Conductive Hearing
Loss
Acoustic Reflex Results-Self Test #1
Acoustic Reflex Results-Self Test #2
Interpretation of Objective Tests
Acoustic Reflex Conclusion
Acoustic Reflex Threshold results are part of a battery of tests to help
evaluate the patient
As clinicians we need to combine the results from otoscopy, immittance
testing (static acoustic compliance, tympanometry and acoustic reflex),
audiometric threshold testing for air conduction and bone conduction and
speech audiometry testing to make appropriate recommendations
Additional electroacoustical and electrophysical procedures are available and
will be studied as part of the AuD degree
Textbook Chapter 6 Overview: (**Refer to Lesson 11**)
ComD 3700 Course Notes-Lesson 14
4/19/11 11:08 PM
Lesson 14
Outer and Middle Ear Disorders
Outer Ear-Anatomy Review
Middle Ear-Anatomy Review
Outer Ear
Outer Ear Disorders
Disorders of the outer ear result in conductive hearing loss
Otoscopy
Otoscopy is shining a light in the ear in order to view the status of the ear
canal and ear drum
Healthy Tympanic Membrane
Disorders of the Auricle
Usually there is no hearing loss
Sometimes malformations of the auricle are associated with other disorders
and do not stand as an isolated disorder
Microtia
abnormally small
Macrotia
abnormally large
Anotia
missing or absent
Otoplasty or Pinnaplasty
surgery to reconstruct malformed auricles
Disorders of the External Auditory Canal
Atresia: Closed Ear Canal
Conductive hearing loss
Causes:
• Congenital
o Many times with congenital ear canal disorders, the middle
and sometimes the inner ear is also involved
§ Treacher Collins Syndrome
§ CHARGE syndrome
• Trauma
o Hematoma
o Exposure
§ Sunburn
§ Frostbite
ú Can lead to a loss of the pinna
ú
Stenosis: Narrowing of the ear canal
No hearing loss unless canal becomes closed
Problems with cerumen build-up
Collapsing Ear Canal
Occurs naturally
Young children
Elderly
Occurs during audiometric testing
Earphones cause auricle to move forward
Insert earphones should be used
Foreign Bodies
Foreign object is placed or enters the ear canal
May require surgery to remove
Examples include
• Paper, Beads, Button Batteries
• Food-Beans, Peas
• Insects-Ticks, Ants
External Otitis ( Infection in the EAC)
Swimmer’s Ear
Bacteria formation (most common)
Fungus in some cases
Symptoms:
• Pain
• Swelling (edema)
• Redness
• Exudate = fluid discharge
Treatment:
• Cleansing
• Applying antibiotic
• Cotton wick
Hearing tests are sometimes impossible because of pain and the presence of
infection
Hearing loss is related to occlusion of the ear canal
External Otitis
Cerumen (Ear Wax)
Glands produce excessive wax
Ear canal abnormally narrow
Hearing loss related to occlusion of the ear canal
Treatment:
Irrigation
Removal by Audiologist, ENT or other professional
Disorders of the Tympanic Membrane
Perforations of the Tympanic Membrane
Hearing loss depends on location of the perforation
Central perforations usually result in greater HL
Myringoplasty
• Surgery involving the TM
The Outer Ear Review
Middle Ear
Middle Ear Disorders
Disorders of the middle ear result in conductive hearing loss
Otitis Media
• ot = ear
• itis = inflammation
• media = middle
Second most common cause of hearing loss in overall population
Most common cause of hearing loss in children
Acute vs. Chronic
General Course of OM:
Blocked eustachian tube
Negative middle ear pressure
Accumulation of fluid
Infection
Complication (necrosis)
Resolution
Otitis Media Treatment
Spontaneous recovery
Antibiotics
Myringotomy
Mastoidectomy
Tympanoplasty
PE tubes
Disorders of the Middle Ear
Suppurative Otitis Media
Infected
Purulent = pus forming
If pressure from pus continues to rise, small blood vessels become blocked
and necrosis can occur in the mucosa
If continued or chronic can result in:
•
•
•
Mastoiditis
Meningitis
Death
Cholesteatoma
Skin introduced to middle-ear causing a pseudo-tumor
Negative ear pressure
Otorrhea is present
Serous Effusion
Fluid in the middle ear that is not infected
Meniscus-Fluid Line
Type B tympanogram
Disorders of the Middle Ear
Mucous Otitis Media
Referred to as “Glue Ear”
Thick adhesions form & bind the middle ear structures
The incidence of mucous OM has increased since the introduction of
antibiotics
Otosclerosis
A focal disease effecting mostly the middle ear (may effect the inner ear)
Formation of new spongy bone which is highly vascular
Can be referred to as otospongiosis
Gradually changes into a dense sclerotic mass
Symptoms appear when functional areas of the auditory system are affected
fixation of the stapes in the oval window
Conductive hearing loss
Hereditary in 70% of cases
Conductive Hearing Loss in Middle Ear Review
Textbook Chapter 8 & 9 Overview:
Chapter 8
The Outer Ear
Learning Objectives
This chapter requires no previous knowledge of human anatomy, but it does
assume an understanding of the physics of sound and the various tests of
hearing described earlier. All the minuscule details of the anatomy of the
outer ear are not provided in the text. These may be obtained readily from
books on anatomy. Upon completion of Chapter 8, the reader should be
able to:
Discuss in basic terms the outer-ear anatomy and its purpose.
List a variety of common disorders that may affect the outer ear.
Describe how these disorders are caused and treated and how they may
manifest on a variety of audiometric tests.
Summary
The outer ear, including the auricle, external auditory canal, and tympanic
membrane, is the channel by which sounds from the environment are first
introduced to the hearing mechanism. The auricle helps gather the sound,
the external auditory canal directs it, and the tympanic membrane vibrates
in sympathy with the airborne vibrations that strike it. When portions of the
outer ear are abnormal or diseased, hearing may or may not become
impaired, depending on which structures are involved, and the nature of
their involvement.
Abnormalities of the external ear do not affect the sensorineural mechanism.
However, alterations in the canal may cause a change in the osseotympanic
mode of bone conduction, which may alter the bone-conduction curve
slightly. Audiometric findings on word-recognition and site-of-lesion tests are
the same as expected for persons with normal hearing. Measurements on
the acoustic immittance meter are frequently impossible in external-ear
anomalies, by virtue of the disorder itself.
Whenever an audiologist sees a patient with an external-ear disorder, an
otological consultation should be recommended. If hearing is impaired and
no medical therapy is available, audiological treatment options should be
investigated, depending on the extent of the hearing loss, and the needs of
the patient.
Outline
Anatomy and Physiology of the Outer Ear
Development of the Outer Ear
Hearing Loss and the Outer Ear
Disorders of the Outer Ear and Their Treatments
Vocabulary
Anotia
Annulus
Atresia
Auricle
Cerumen
Condyle
Down syndrome
Ectoderm
Entoderm
Exostoses
Osseocartilaginous junction
Osteitis
Osteomyelitis
Otalgia
Otomycosis
Otoplasty
Otoscope
Pars flaccida
Pars tensa
Pharyngeal arches
External auditory canal
External otitis
Furunculosis
Meatus
Mesenchyme
Mesoderm
Microtia
Mucous membrane
Myringitis
Myringoplasty
Pinna
Pinnaplasty
Pneumatization
Shrapnell's membrane
Stenosis
Temporomandibular joint
syndrome
Tympanic membrane
Tympanosclerosis
Umbo
Chapter 9
The Middle Ear
Learning Objectives
This chapter assumes a basic understanding of hearing loss as introduced in
Chapter 2, the physics of sound in Chapter 3, and the details of hearing tests
and their interpretation in Chapters 4 through 8. Oversimplifications of the
anatomy of the middle ear and its function, provided as an introduction
earlier in this book, should be clarified. At the completion of this chapter,
readers should:
Understand the anatomy and physiology of the middle ear.
Be familiar with some of the etiologies and treatments of common disorders
that produce hearing loss.
Be able to predict what the typical audiometric results for each of the
pathologies might be.
Be able to make a reasonable attempt at diagnosing the etiology of the
hearing loss based on audiometric and other findings.
Summary
The middle ear is an air-filled space separating the external auditory canal
from the inner ear. Its function is to increase sound energy through
leverage, the step-down ratio provided by the ossicular chain, and the area
ratio between the tympanic membrane and the oval window
Abnormalities of the structure or function of the middle ear result in
conductive hearing losses, wherein the air-conduction thresholds are
depressed in direct relationship with the amount of disease. Boneconduction thresholds may deviate slightly from normal in conductive
hearing losses, not because of abnormality of the sensorineural mechanism,
but because of alterations in the middle ear’s normal (inertial) contribution
to bone conduction. Alterations in pressure-compliance functions give
general information regarding the presence of fluid or negative air pressure
in the middle ear, stiffness, or interruption of the ossicular chain.
Measurements of static compliance may be higher or lower than normal and
acoustic-reflex threshold sensation levels are either elevated or the response
is absent. Auditory brainstem responses show increased latencies for all
waves and otoacoustic emissions are usually absent. Results on wordrecognition tests are the same as for those with normal hearing.
Remediation of middle-ear disorders should first be concerned with medical
or surgical reversal of the problems. When this fails, must be postponed, or
is not available, careful audiological counseling should be undertaken and
treatment avenues, such as the use of hearing aids, investigated. Provided
no medical contraindications to hearing-aid use and no planned medical or
surgical intervention exist, patients with conductive hearing losses are
excellent candidates for hearing aids because of their relatively flat
audiometric contours, good word recognition, and tolerance for loud sounds.
Outline
Anatomy and Physiology of the Middle Ear
Development of the Middle Ear
Hearing Loss and the Middle Ear
Disorders of the Middle Ear and Their Treatments
Vocabulary
Acute
Necrosis
Aditus ad antrum
Ossicles
Autophony
Otitis media
Barotrauma
Otorrhea
Bell’s palsy
Otosclerosis
Carhart notch
Otospongiosis
Carotid artery
Oval window
Cholesteatoma
Paracusis willisii
Chorda tympani nerve
Chronic
Cilia
Crura
Crus
Epitympanic recess
Eustachian tube
Facial nerve
Fallopian canal
Fascia
Fenestration
Fistula
Footplate
Hemotympanum
Incus
Jugular bulb
Lombard voice process
Meniscus
Middle-ear
Mucous membrane
Myringotomy
Nasopharynx
Physical-volume test (PVT)
Politzerization
Pressure-equalizing (P.E.) tube
Promontory
Purulent
Round window
Schwartze sign
Serous effusion
Stapedectomy
Stapedius muscle
Stapes
Stapes mobilization
Subluxation
Suppurative
Tensor tympani muscle
Tinnitus
Toynbee maneuver
Trigeminal nerve
Tympanoplasty
Tympanosclerosis
Umbo
Valsalva
ComD 3700 Course Notes-Lesson 15
4/19/11 11:08 PM
Lesson 15
Inner Ear Disorders
Inner Ear-Anatomy Review
Inner Ear Disorders
Inner ear disorders cause sensorineural hearing loss
May be organized into:
• Prenatal Causes
o Existing or occurring before birth
Perinatal Causes
o Occur during the process of birth itself
• Postnatal Causes
o Occur after birth
o
Prenatal Causes
• Genetic Factors
• Rh Factor
o Problem occurs when a protein molecule known as the Rh
factor is present in the fetal blood but absent in the mother’s
blood
o Antibodies begin to increase in the mother until red blood
cells of fetus are damaged
o With successive pregnancies, the antibodies become more
and more effective
o Much less frequent today than in the past with maternal
immunizations and fetal blood transfusions
• AIDS or HIV
o Mothers with HIV have a 50% chance of delivering a baby
with the disease
o Can cause SNHL
• Viral Infections
•
•
Cytomegalovirus (CMV)
o Seemly harmless virus
o Herpes group
o When the fetus is infected, a variety of physical difficulties
can be present
Perinatal Causes
• Anoxia
o Lack of oxygen
o Results in multiple physical disorders
• Toxemia
o Accumulations of toxic substances in the maternal blood
crosses the placenta and causes damage to the fetus
• Prematurity
o Incidence of hearing loss is 2-6%
o May be caused by noisy environment
o
Postnatal Causes
• Otitis Media
• Meningitis
• Labyrinthitis
• Barotrauma
• Ototoxic Drugs or Agents
o Mycin family
o Quinine (used in the past)
o Aspirin
o Nicotine
• Noise Induced Hearing Loss
o TTS = temporary threshold shift
o PTS = permanent threshold shift
o Historically affected males more than females
o Now a problem with teenagers as well
o Symptoms
§ Sensorineural hearing loss
§ 4000 Hz notch in audiogram
§ Tinnitus
§ Discrimination difficulties
o Treatment
§ Ear Protection
o Industrial Audiology
OSHA
Occupational Safety & Health Administration
Guidelines:
85 dB = 8 hours
90 dB = 4 hours
95 dB = 2 hours
100 dB = 1 hour
105 dB = .5 hour
Recreational Activities
Motorboats, motorbikes, racecars, hunting, musicians, snowmobiles
Meniere’s Disease
Endolymphatic hydrops
Over production or under secretion of Endolymph
As pressure builds in Cochlear Duct hair cells become affected causing
tinnitus and hearing loss
Vestibular mechanics become involved causing vertigo
The triad
• Fluctuating SNHL
• Vertigo
• Roaring tinnitus
Onset of symptoms described as:
• Fullness in the ear
• Low frequency roaring tinnitus
• Hearing loss
• Great difficulty in speech discrimination
• Violent vertigo
Onset between 40-60 years of age
• 50% of the cases
Attacks followed by periods of remission
Diagnosis
• Flat fluctuating unilateral SNHL
• Roaring tinnitus
• Dizziness
• Excessively poor speech discrimination
Treatment
• Diuretics
• Shunting
• Surgically destroy the labyrinth
Presbycusis
Hearing Loss due to aging
Cumulative effects of:
• Infections
• Toxins
• Trauma
Gradual retrogressive changes in:
• cell function
• cell structure
• cell numbers
Aging process affects auditory areas other than just the cochlea
• Tympanic membrane
• Ossicular chain
• Cochlear windows
• Central auditory nervous system
Schuknecht (1993) causes of presbycusis
Sensory
Neural
Strial
Cochlear conductive
Presbycusis
Patient Characteristics
• Bilateral SNHL
• Absence of recruitment
• Gradual progressive bilateral SNHL
Treatment
•
Amplification
Common Causes of SNHL According to Age at Onset
Textbook Chapter 10 Overview:
Chapter 10
The Inner Ear
Learning Objectives
This chapter describes the inner ear as a device that provides the brain with
information about sound and the body’s position in space. Once this chapter
has been completed the reader should be able to:
Identify the anatomical landmarks of the inner ear mechanism.
Briefly describe the contributions of the inner ear to hearing and spacial
orientation.
List a variety of disorders that affect the inner ear and give their causes
stating whether they would normally be prenatal, perinatal or postnatal in
origin.
Discuss the probable results on auditory tests described earlier in this book
as they may relate to inner-ear disorders.
Summary
The inner ear is a fluid-filled space, interfaced between the middle ear and
the auditory nerve. It acts as a device to convert sound into a form of
electrochemical energy that transmits information to the brain about the
frequency, intensity, and phase of sound waves. The vestibular portion of
the inner ear provides the brain with data concerning the position and
movement of the body.
When the cochlear portion of the inner ear becomes abnormal, the result is a
combination of sensorineural hearing loss and dysacusis. Bone-conduction
and air-conduction results essentially interweave on the audiogram, and
word recognition generally becomes poorer in direct relation to the amount
of hearing loss. Results on tympanometry and static immittance in the plane
of the tympanic membrane are usually within normal limits, unless the
sensorineural loss has a superimposed conductive component, resulting in a
mixed hearing loss. Acoustic reflex thresholds are expected at low sensation
levels. In pure cochlear hearing losses the latency-intensity functions
obtained from ABR testing are rather steep, showing longer latencies close
to threshold. If the outer hair cells are damaged, causing more than a mild
hearing loss, otoacoustic emissions will be absent.
If any of the behavioral site-of-lesion tests discussed briefly in Chapter 6 are
performed, patients with cochlear hearing loss are expected to show high
SISI scores and moderate amounts of tone decay (especially in the higher
frequencies). Recruitment of loudness can usually be found, which often
complicates auditory rehabilitation.
Habilitation or rehabilitation of patients with sensorineural hearing losses of
cochlear origin is considerably more difficult than for patients with
conductive lesions. Medical or surgical correction is usually obviated by the
very nature of the disorder; however, there are several important exceptions
to this. Combinations of harmonic and frequency distortion and loudness
recruitment often make the use of hearing aids difficult but not impossible.
Auditory rehabilitation of patients with cochlear disorders is of special
concern to audiologists.
Outline
Anatomy and physiology of the inner ear
Development of the inner ear
Hearing loss and disorders of the inner ear
Causes of inner-ear disorders
Vocabulary
Acoustic trauma notch
MeningitisÊ
Acquired immune deficiency syndrome (AID NeuronÊ
S)
NeurotransmissionÊ
Action potential (AP)Ê
NeurotransmitterÊ
Afferent
NystagmusÊ
AlleleÊ
Organ of CortiÊ
AmpullaÊ
Otoacoustic emissions (OAE)
AnoxiaÊ
OtocystÊ
AthetosisÊ
OtotoxicÊ
Auditory placodeÊ
Autosomal dominantÊ
Autosomal recessive
PerilymphÊ
Permanent threshold shift (PTS)Ê
PhenotypeÊ
AutosomeÊ
AxonÊ
Basilar membraneÊ
Caloric testÊ
CarrierÊ
Cell bodyÊ
CerebellumÊ
Cerebral palsyÊ
ChromosomeÊ
CochleaÊ
Cochlear ductÊ
Phonemic regression
Place theory of hearingÊ
PresbycusisÊ
Psychophysical tuning curve (PTC)Ê
ReissnerÕs membraneÊ
Resonance theory of hearingÊ
Resonance-volley theory of hearingÊ
Retrocochlear
Rh factorÊ
SacculeÊ
Scala mediaÊ
Cochlear microphonic (CM)Ê
Computerized dynamic posturography (CDP
)
CortiÕs archÊ
Cytomegalovirus (CMV)Ê
Damage-risk criteriaÊ
DendriteÊ
DiplacusisÊbinauralis
Diplacusis monauralis DNAÊ
Ductus reuniensÊ
DysacusisÊ
EfferentÊ
Electronystagmograph (ENG)
Endogenous
Endolymph
Exogenous
Frequency theory of hearing
Gene
GenotypeÊ
Glycerol testÊ
HelicotremaÊ
Hereditodegenerative hearing lossÊ.
Scala tympaniÊ
Scala vestibuli
Semicircular canalsÊ
Mixed hearing lossÊ
ModiolusÊ
Multifactorial genetic considerationsÊ
Sensorineural hearing loss
SomatosensoryÊ
Spiral ligament
Spontaneous otoacoustic emissions (SOAE)
Stereocilia
Stria vascularis
SynapseÊ
SyndromeÊ
Tectorial membrane
Temporary threshold shift (TTS)
TransduceÊ
Transient-evoked otoacoustic emissions (TE
E)
Traveling wave theoryÊ
TrisomyÊ
UtricleÊ
HeterozygousÊ
HomozygousÊ
Human immunodeficiency virus (HIV)Ê
Variable expressivityÊ
Vasospasm
VertigoÊ
HypacusisÊ
LabyrinthÊ
Labyrinthitis
M ni re disease
VestibuleÊ
Volley theory of hearingÊ
X-linkedÊ
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement