"Audiologists serve in a number of roles including clinician, Therapist, teacher, consultant, researcher, and administrator. The supervising audiologist maintains legal and ethical responsibility for all assigned audiology activities provided by audiology assistants and audiology students."
Specific Roles of Audiologists:
Evaluate and diagnose hearing loss and vestibular (balance) disorders.
Prescribe, fit, and dispense hearing aids and other amplification and hearing assistance technologies
design and implement hearing conservation programs.
design and implement newborn hearing screening programs
provide hearing rehabilitation training such as auditory training and listening skills improvement
assess and treat individuals, especially children, with central auditory processing disorders
assess and treat individuals with tinnitus (noise in the ear, such as ringing)
Word War II
Physicians and hearing aid dealers provided hearing care prior to war
The war caused a shift of practice to "audiology,"a term made famous by Raymond Carhart around 1945.
The hearing care industry jump started audiology into a profession due to the presence of military based aural rehab centers.
Soldiers returning from war needed treatment for hearing loss due to excessive high noise levels
Increased success in the military provided the transition to the civilian sector.
Academic Preparation
The profession of audiology continues to expand its scope of practice due to the increasing rate of technology advances in the hearing health care industry.
Degrees Include: B.S, M.S., Au.D.,Sc.D.,PhD.
Since _MM/DD/YYYY__, it is required for audiologists to receive a doctorate in audiology to practice in the field and to become certified by national organizations.
January 1st, 2007
Licensing and Certification
Regulated by a licensing body or registration in the US for every state
Licensure is a legal requirement to practice in the field of audiology
An audiology license requires completion of required course work, 2,000 hours of clinical practicum and obtaining a passing score on a national examination
Certification is not a legal requirement, although is necessary to obtain when dealing with an ASHA accredited university.
State Licensing
OBESPA
ASHA
CCC- Certificate of Clinical Competence
AAA
FAAA- Fellow of the American Academy of Audiology
ABA
Board Certified Audiologist
Prevalence and Impact of Hearing Loss
Prevalence of hearing loss increases with age
Causes of hearing loss may include excessive noise exposure, middle ear pathologies, anatomical anomalies,trauma, genetics, medications and unknown etiologies
Hearing impairment causes mild to sever communication difficulties for people of all ages.
It is most detrimental to children who are developing speech and language.
Table 1.1 Prevalence
50 million have tinnitus
30 million exposed to hazardous noise levels
26 million are hard of hearing
10 million have some degree of permanent noise-induced hearing loss
2 million are classified as deaf
Approx. 6 out of 1000 may be born with hearing impairment
Approx 15% of school age kids may fail a school hearing screening due to an ear infection
Before age 6, 90% of children in the US will have had at least one ear infection
Prevalence and Impact
People with hearing loss have an increased difficulty understanding speech, especially in the presence of noise
Impact is greatest on prelingual children, but also affects postlingual children and adults due to psychosocial aspects
Diagnosis of hearing loss is essential to maintain language acquisition, interact with family/peers, decrease negative educational impact and for psychological well-being and self-perception.
Hearing Loss Impact
Bess, et al. (1989)- Progressive hearing loss in older adults is associated with progressive physical and psychosocial function.
Grundfast and Carney (1987)- annual costs for treatment of childhood ear infections may be as high as $2 billion in the US
1 out of 6 baby boomers ages 41 to 59 have a hearing loss
Hearing aid use can reduce loss of income by approximately 50%
Approximately 1 out of every 4 with a loss seek treatment
Due to psychosocial/psychological impact, audiologists may sometimes take on a counseling role to aid the patient in acceptance
Clinical Commentary
SLPs often find they work in close concert with audiologists
It is this frequent coexistence of hearing disorder and speech/language problems that has led the American Speech-Language-Hearing Association to include hearing screening procedures, therapeutic aspects of audiologic rehabilitation, and basic checks of hearing aid performance within the SLP's scope of practice.
Job Settings
Medical: contains the largest amount of audiologists
Work in diagnostic assessment and aid medical doctors in final diagnosis
Educational: work in the school system
Less than half the amount needed actually work in the school system
Identify and refer kids with hearing loss to medical
Pediatrics: focus on the diagnosis and aural rehabilitation of children
Primary role is to incorporate/facilitate the parents' efforts to meet the rehab challenges the child and family will face.
Job Settings
Dispensing/Rehab: primarily fit and dispense hearing aids and provide aural rehab
Primarily involved in private practice
Industrial Audiology: work to prevent noise-induced occupational hearing loss
Set up hearing conservation programs, provide info on hearing protection and monitor hearing sensitivity
82% consider themselves clinical service providers
The 2 major areas of employment setting are Medical Setting and Private Practice
Field of Science concerned with how the body works
Anatomy
Field of Science concerned with how the body functions
Physiology
Outer Ear
Pinna
Helix
Concha
Lobule
Tragus
Anti-tragus
External Auditory Canal/Meatus (EAC)
Middle Ear
Tympanic Membrane (TM) aka eardrum
Ossicular chain
Malleus-connects to TM (hammer)
Incus (Anvil)
Stapes (stirrups)
Eustachian tube
Inner Ear
Oval Window; area where stapes attaches to cochlea
Cochlea: Hearing Mechanism
Round Window
Semi-circular canals: Balance
VIII Nerve
Facial Nerve: 12th nerve
Outer Ear
The aurical or pinna is the largest portion
It's shape allows sound to funnel into the EAC
It gathers environmental sounds
Aids in localization
Outer Ear
External Auditory canal (EAC)
The opening begins at the concha
Extends toward the midline at an upward angle in adults and is approximately 1 inch
Outer portion passes through cartilage: contains hair follicles
Inner portion runs to the TM: no glands or hair follicles for this portion
Provides protection for the TM
Acts as a filter for sounds
Tympanic Membrane
Beginning of the middle ear
Provides a barrier between the outer elements
Protects the middle ear from external pathogens
Extremely thin and subject to trauma
Smallest bone in the human body
Stapes
Eustachian Tube
Connects the middle ear to the back of the throat(nasopharynx)
Provides aeration to the middle ear to keep it bathed in air
Inner Ear
Cochlea
Connected to the middle ear by the stapes fitting into the oval window
Fluid filled spaces aid in the transmission of sounds to the auditory nerve (8th nerve)
Inner Ear
Semi-Circular Canals
3 canals that lie at 90 degree angles of each other
They are membranous and are contained in a larger bony cavern
Primarily responsible for balance
Pathways of Sound
Air Conduction: depends on the functioning of the outer, middle and inner ear and also the neural pathways beyond
Bone Conduction: bypasses the outer and middle ear and relies on the inner ear and beyond
Types of Hearing Loss
Conductive Hearing Loss
Attenuation: decrease in the strength of sound
Blockage of the outer and/or middle ear will result in a conductive loss and an attenuation of sound
Impaired air conduction (AC) with normal bone conduction
Sensorineural Hearing Loss (SNHL)
The hearing loss by bone conduction (BC) will be as great as the loss by air conduction (AC)
When the same amount of attenuation is present for BC and AC, the conductive mechanism can be ruled out
Intact outer/middle ear, but problems with cochlea or pathways beyond
Mixed Hearing Loss
Problems occur in both the conductive and sensorineural components
Loss is present due to sensorineural abnormality, but conductive loss is greater
Conductive loss is greater due to attenuation by the outer and/or middle ear plus inner ear problems
Nonorganic Hearing Loss
Either have normal hearing or insufficient auditory pathology to explain the extent of the loss
Consciously faking for financial gain (malingering) or a psychological disorder manifested a symptom of hearing loss (psychogenic hearing loss)
Hearing Tests
Early hearing testing consisted of the use of noisemakers, hand claps, pocket watches, tuning forks, etc.
Today’s technology allows for frequency specific testing to locate the area of dysfunction along the auditory pathway
Tuning Fork Testing
Emits a tone at a particular pitch and has a clear musical quality
The air conduction tone that is emitted is a relatively pure tone that is free of overtones
Set into vibration by holding the stem and striking the tines against a firm surface
Any diagnostic value is limited to the specific pitch of the fork
Tuning Fork: Schwabach Test
A bone conduction test.
Compares the patient’s hearing to the examiner
Stem is placed on the mastoid process
Normal = stop hearing at the same time
Diminished = patient stops hearing before examiner (SNHL)
Poorly diagnoses CHL and MHL
Tuning Fork: Rinne Test
Compares BC to AC
Stem is placed on mastoid and tines are placed near the pinna
Positive: normal or SNHL – louder next to ear than behind the ear
occlusion effect – close off ear canal and the BC loudness increases
Primarily low pitched sounds
Present for SNHL, but absent with CHL
Positive: normal/SNHL – change in loudness during open and close of ear canal
Negative: CHL – no change in loudness as canal is opened and closed
Tuning Fork: Weber Test
Tests lateralization (left, right, both or midline)
Stem is placed on forehead (midline)
Normal/same amount of loss: midline
SNHL: hear tone in better ear
CHL: hear tone in poorer ear
2 equal tones presented with different loudness levels, the louder will be perceived
Stenger Principle
Tuning Fork Info
Tuning fork tests are not used regularly by audiologists due to technology advancements
Otologists still use forks for quick, in office testing
What is Sound?
Defined in terms of psychological or physical phenomena
Sound is an auditory experience – the act of "hearing" something, means it is _____.
Psychological
A series of disturbances of molecules in an elastic medium such as air.
Physical
It is essentially a form of energy.
Elasticity
Essentially the springiness of a medium.
Increases as the distance between molecules is decreased
If you squeeze a rubber ball, it temporarily changes shape, but eventually restores its original shape
The rate at which this occurs is the elasticity
Solids are more closely “packed” together, so a solid is more elastic than a liquid
Vibration
Vibration is the source of the creation of sound
Refers to the back and forth motion of a mass
The energy created by vibrations create a point of disturbance in a medium, striking and bouncing off adjacent molecules
Waves
Definition: succession of molecules being shoved together and pulled apart
Made up of successive compressions and rarefactions
When molecules are forced closely together and thus create increased or higher pressure it is called _____.
Compression
When molecules move further apart and create decreased or lower pressure (less condensed)it is called _____.
Rarefraction
A type of wave in which, the motion of the molecules is perpendicular to the direction of the wave medium. Example: dropping a pebble in water.
Transverse
A type of wave in which, molecules vibrate parallel to the direction of the wave medium. Example: wheat in the wind. Do not have crests or troughs b/c they do not move up an down.
Longitudinal
Moving energy equals
Kinetic Energy
Essentially stored up energy
Potential energy
As objects are in movement, they encounter resistance by molecules in the air.
This friction converts some of the energy in the initial movement of the object into heat
Friction causes the object to slow down its movement
One compression and one rarefaction of a sound wave is called a ________.
Cycle
The number of cycles of vibration completed during a time period is called _________.
Frequency
In acoustics, the reference unit of time is usually
Seconds
Cycles per second:
if the time required to complete a cycle is one second, the frequency would be noted as 1 cycle per second (cps)
More commonly used instead of cps when describing the unit of frequency of sound...
Hertz
As ________ decreases, frequency increases. ex: strings on an instrument (shorter string = higher frequency)
Length
As ________ increases, the frequency decreases. Ex: increased thickness of musical strings = lower tones
Mass
As ________ increases, the frequency at which the body is most easily made to vibrate decreases.
Compliance
The natural rate of vibration of a mass is called its ____________.
Resonant Frequency
Resonant Frequency
When an object is oscillating at an optimum rate and amplitude
This is the optimum frequency of a vibrating object due to its characteristics
Resonant frequency is why a glass may shatter when a perfect note is played in its presence
Defined as the distance from the baseline to the point of maximum displacement of a wave...The distance the mass moves from the point of rest. Determines the intensity of sound and is related to the force with which the original particle disturbance was created. Increased intensity = increased ______
Amplitude
An objective (able to be seen; measureable; physical) term and is the amount of sound energy per unit of area is called __________.
Intensity
A subjective (not tangible; psychological) impression of the power of a sound is called _________.
Loudness
The speed with which a sound wave travels from the source to another point is called_________.
Velocity
Velocity
Elasticity, density and temperature all influence velocity
Sounds travel faster through solids than through liquid and faster through liquid faster than gas due to density of the object.
When velocity is increased, acceleration takes place
Wavelength
The length of a wave is measured from any point on a sinusoid (0-360 degrees) to the same point on the next cycle of the wave
Wavelength = velocity of sound/frequency
W=v/f
Difficulty hearing someone who is speaking in another room occurs due to...
The longer wavelengths of the lower frequency sounds of vowels more easily move around corners and obstructions than do the shorter wavelengths of the higher frequencies contained in many of the consonants of speech.
The relationship in time between two or more waves is called ______.
Phase
Different points in the wave can be compared to a standard to determine if they are in phase.
A sound that has all its energy at 1 frequency, creating a pure tone is called a _______.
Simple Sound
Does not occur naturally
Created by tuning forks and pure-tone audiometers
A sound that has energy at more than 1 frequency is called a _______.
Complex Sound
Ex: Sound created with the human voice, musical instruments and other environmental sounds
The lowest rate of a sound’s vibration. Determined by physical properties of the vibrating body.Essentially the lowest resonant frequency.
Fundamental Frequency: AKA 1st harmonic
Harmonics AKA Overtones
all frequency whole-number multiples of the fundamental
The 1st harmonic is the fundamental and the 2nd harmonic is twice the fundamental.
Ex: fundamental = 100, so then 200, 300, 400
Complex Sounds
Although the fundamental frequency determines all the harmonic frequencies, the harmonics do not have equal amplitude
The fundamental frequency in the human voice is controlled by the vocal folds in the larynx
By raising or lowering the tongue and moving it forward or back, it changes the frequency and intensity that emphasize some harmonics more than other, changing the amplitudes.
The resulting waveform has peaks and valleys
Each of the energy peaks are called _______.
Formants
Manipulation of formant frequencies aid in recognition of different vowel sounds.
The peaks are numbered consecutively.
Expressed as lowest/first (F1), second (F2) and so on.
Once the fundamental has been determined, the fundamental is no longer essential for the perception of sound for people with normal hearing.
Average Male fundamental voice frequency
85-150 Hz
Average Female fundamental voice frequency
175-250 Hz
__________ is Generated whenever force is distributed over a surface area.
Pressure
Pressure
If an area remains constant, the pressure increases as the force is increased
Due to human hearing sensitivity, micropascals (µ Pa) are used to express sound pressure
The smallest pressure variation required to produce a just-audible sound to a healthy young ear is approximately 20 µ Pa
The unit of measurement used in audiology for intensity
Decibel
Decibel
Named after the inventor of the telephone, Alexander Graham Bell
A decibel (dB) is 1/10 of a Bel
5 Important Aspects of the Decibel
It involves a ratio
It utilizes a logarithm
It is therefore non-linear
It may be expressed in terms of various reference levels
It is a relative unit of measure
The decibel scale has 2 main implications
Rather than all units of measurement being the same size, each unit is larger than the preceding unit
We can compress a wide range of sound pressure between the highest tolerable sound pressure and the sound pressure that can just be heard into a manageable scale ranging from 140 to 0 dB
The decibel has no absolute zero
This means 0 dB is an intensity value and is not the absence of sound (audiogram)
Intensity Level:Audiologist do not use this level clinically.Primarily used for electrical systems or equipment. The reference for IL is _________.
Watts (W)
Sound Pressure Level (SPL)
Audiologist and acousticians are more accustomed to making measurements of sound in pressure than in intensity terms
Used to describe pressure ratios
For audiology terms, the reference for sound pressure is
.0002 dyne/cm2 or O dB SPL
O dB SPL is the smallest amount of sound pressure that will set a human eardrum into motion
Sound Pressure Level (SPL)
O dB SPL does not mean silence, only that the output pressure is O dB above the reference pressure.
Therefore, 20 µPa is O dB SPL
The ear threshold of pain is ______.
140 dB SPL
When sound pressure levels are doubled, the # of decibels are increased by __ because they are ratios.
6. ex: 60 dB + 60 dB = 66 dB
The lowest sound intensity that stimulates normal hearing is called _______.
zero hearing level (HL)
Hearing Level
Used because the ear shows different amounts of sensitivity to different frequencies, so different amounts of pressure are required to stimulate hearing sensitivity
Most sensitive from 1000-4000Hz range
Written by audiologists as dB HL when dealing with audiograms
The number of decibels of a sound above the threshold of a given individual is the sound’s _______.
sensation level (SL)
Sound Sensation Level is used in reference to the auditory _______ of a given individual.
threshold
A ____ ____ threshold is defined as the level at which the tone is so soft that it can be perceived only 50% of the time it is presented.
pure tone
If a person can barely hear a tone or speech sound at 5 dB HL, this same sound presented at 50 dB HL will be 45 dB above their threshold (45 dB SL). The same 50 dB HL tone presented to a person with a 20 dB threshold will have a sensation level of ____.
30 dB SL
In order to state the person's dB SL, the threshold of the individual (the reference) must be known.
Factors of Sound that remain the same with or without human perception is ___________.
Physical Acoustics
The study of the relationship between physical stimuli and the psychological responses to which they give rise is called ______________.
Psychoacoustics
The subjective impressions of the "highness" or "lowness" of a sound is called ________.
Pitch
Pitch relates to _______.
Frequency
Pitch rises as the frequency of vibration ________.
Increases
Range of human hearing is approximately ______________.
20 to 20,000 Hz (frequencies)
A subjective experience (perception), as contrasted with the purely physical force of intensity is called _____.
Loudness
Duration and frequency of sounds contribute to the sensation of _____________.
Loudness
dB is not a unit of _________.
Loudness
____________ grows faster for low frequency tones and especially for high frequency tones than for mid-frequencies.
Loudness
The ability to tell which direction the sound is coming from refers to __________.
Localization
Localization
Results from complex interactions between both ears. Thought to be an early survival skill in the human species. Possible due to relative intensities of sounds and their arrival to two ears (phase). Highly dependent on phase differences in the lows (below 1500Hz) and intensity differences in the highs.
When two sounds are heard at the same time, the intensity of one sound may be sufficient enough to cause the other to be inaudible, which is called _______.
Masking
The change in the threshold of a sound caused by a sound with which it coexists is called _________.
Masking
Being in a crowded room and not being able to understand a speaker due to the crowd noise (speech interference) is an example of what?
Masking
The opposition that a medium offers to the transmission of acoustic energy is the definition of _______.
Impedance
Impedance
The more dense an object, the reater the impedance to the sound wave
Greater impedance = smaler amplitude
Greater mass attenuates higher-frequency sounds more that lower-frequency sounds
What frequencies carry the majority of speech sounds?
mid and highs
Impedance is determined by what two factors
Simple resistance and Complex resistance
Resistance that is not influences by frequency of vibration is __________.
Simple resistance
Resistance that is influenced by frequency; opposition to energy varies with frequency is __________.
Complex resistance (reactance)
_______ reactance is determined by mass and stiffness reactance.
Total
As physical stiffness of an object increases, so does _________.
Stiffness reactance; as frequency increases, stiffness reactance decreases (inverse relationship)
As physical mass of an object or the frequency at which the object vibrates is increased, so does the _____.
mass reactance; directly related to both mass and frequency
Audiologist are interested in making what 2 kinds of measurements?
Hearing ability of patients with possible hearing disorder
Sound pressure levels in the environment
The 1st step in quantifying the amount of a patient's hearing loss came with the development of the ______.
Pure tone audiometer: Allows for a comparison of any person's thresholds to that of an established norm.
The intensity at which a tone is barely audible is one's ____________.
Hearing threshold
The number of dB above/below the average normal hearing person's thresholds for different pure tones (0 dB HL) is one's _____________.
Hearing sensitivity
Pure Tone Audiometer
Consists of an audio oscillator (generates pure tones of different frequencies)
Each tone is amplified to a max of about 110 dB from 500-4000 Hz, with less output above/below these frequencies.
Tones are attenuated by using a manual dial or electronic attenuator.
As the number is increased, attenuation is decreased.
Like a volume dial on a home theater system.
Air Conduction
Earphones are held in place by a steel headband. Consists of a magnetic device that transduces the electrical translations supplied by the audiometer to a small diaphragm that vibrates according to the acoustic equivalents of frequency and intensity.
Headphones placed on the outside of the ears.
Supra-Aural Headphones
Bone Conduction
The vibrator is placed against the skull on either the forehead or mastoid process.
The plastic shell of the vibrator must be set into motion.
Vibrating the skull (increased mass)requires greater energy than AC to generate a level high enough to stimulate normal hearing.
Frequencies from 250-4000 Hz are used.
Device used for bone conduction.
Bone conduction Oscillator
Speech Audiometer
Part of a clinical audiometer
Input signal is provided by a mic or CD player
Input level of the signal is monitored by an averaging voltmeter called a VU meter
Signal can be presented via AC, BC, or sound field
Sound Field
Begins by placing the patient in the sound suite and seating them in a chair.
Loudspeakers are placed in the suite and provide the output of a signal
Earphones are NOT used in this type of audiological testing.
Sound Level Meters
Consist of a mic, amplifier, attenuator and a meter that picks up and transduces pressure waves in the air, measures them electrically and reads out the sound pressure levels in decibels
Used to measure background noise levels and are useful in the study of acoustics.
Calibration of audiometers
It is a requirement to have annual calibration checks of audiometers.
Audiologists perform bologic checks more frequently to monitor their audiometers
Assumption of a properly working audiometer without frequent checks can be costly to the audiologist and patient.
Effectiveness of testing relies primarily on what 2 general factors?
Reliability: how well a test result is repeatable
Validity: whether a test measures what it is supposed to measure
Testing results in 1 of 4 ways
True Positive: indicates a disorder correctly
True Negative: Eliminates an incorrect diagnosis
False Positive: Suggests a diagnosis incorrectly
False Negative: Incorrectly eliminates a correct diagnosis
Mathematical model for testing how well it correctly diagnoses a disorder (true positive) is _____.
Sensitivity
Mathematical model for testing how well it rejects an incorrect diagnosis ( true negative); opposite of sensitivity is called ____________.
Specificity
Mathematical model for testing percent of false positive and false negative results is called _______.
Efficiency
Mathematical model for testing percent of true positive and true negative results is called ________.
Predictive Value
Pure Tone Testing
Pure tone tests are essentially electronic extension of the tuning fork tests.
Performing these tests is referred to as audiometry.
Purpose: interpretation of results to determine type and extent of a patient's hearing loss.
Test reliability relies on calibration of equipment, test environment, patient performance, and examiner sophistication.
Audiometry measures patient's responses to stimuli that we interpret as representing hearing.
Pure Tone Audiometer
Used to determine hearing Thresholds, which are compared to a set of norms across specific frequencies.
American National Standards Institute (ANSI) mandates very specific standards for audiometers, so quality or performance should no be an issue.
Pure tone Audiometer
Most audiometers test Air conduction (AC) signals from : 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, and 8000 Hz.
Extended High Frequency audiometers test frequencies from 8000-20,000 Hz
What is the purpose for testing extended high frequencies from 8000 to 20,000 Hz?
Usually for medical or industrial reasons: (chemo-therapy)
Pure tone audiometer
Intensities for air conduction range from -10 to 110 dB HL from 500-6000Hz
Slightly lower intensity for 125, 250, and 8000Hz
Pure Tone Audiometer
Bone Conduction (BC) audiometry tests frequencies from: 250-4000 Hz
50 dB fro 250 Hz and 70-80 dB at 500 Hz and above
Intensity levels are substantially lower than for air conduction because:
The power required to drive the BC vibrator is much greater than for the AC headphones.
The higher intensity causes harmonic distortion, especially in the low frequencies.
High intensities may result in the patient feeling rather than hearing the stimulus (Vibro-Tactile)
Test Environment
Sound-Isolated Chambers
removing all sound from a room is IMPOSSIBLE
Audiologic suites/booths are sound treated to attenuate as much noise as possible
may be custom built or pre-fabricated.
Use of a double or triple pane window allows for sound treatment while preserving the ability to observe the patient's responses
Test Environment
Weakness of Sound Suites/Booths
Ventilation systems
The rooms require a tight enclosure to decrease ambient noise, decreasing air circulation
The use of fans and motors to cool the booth can b troublesome for testing
Sometimes the air is connected directly to the building ducts, but caution is necessary due to the ventilation noise.
Lighting should be INCANDESCENT
Fluorescent lights can put off a 60 Hz hum that can cause a distraction to the patient
Test Environment
Supra-Aural Earphones
Earphone cushions do NOT provide sufficient attenuation of most background noise to get to 0dB HL for normal hearing.
Insert Earphones
Increases attenuation of background noise
The deeper the insertion of the foam plug, the greater the attenuation
Also allows for easier masking for AC and BC
BC Oscillator
Testing does NOT cover the ears, so masking effects of room noise may affect BC, but not AC
Manual Pure-Tone Audiometry
The Patient's Role
Testing patients varies significantly due to age, intelligence, education, motivation and especially cooperation.
Adult vs. pediatric testing techniques vary significantly
Patients usually respond best to instruction given orally
Patients must accept their role and responsibility in testing to obtain reliable,valid responses
Manual Pure-Tone Audiometry
Patient Response
The most important step is to make sure the patient understands the instructions
Instruct the patient to raise their hand as soon as they hear the tone and lower it when they no longer hear it
DO NOT place the earphones on the patient until AFTER the instructions have been fully given.
Manual Pure-Tone Audiometry
Patient Instructions
Response format can vary from raising hand, saying "yes", clapping hands, putting toys in a bucket, pushing a button etc.
Always be aware of false negative and false positive responses
When this occurs in excess, stop testing and reinstruct the patient regarding appropriate responses.
Manual Pure-Tone Audiometry
Clinician's Role
Make patient's aware of their task
Provide verbal, face to face instruction
Remind them to raise their hand ANY time they believe they hear the signal
Tell them you will be testing both ears and what ear you will be starting with
Warn them that the tones will vary in pitch
Loudness is irrelevant; if they hear anything, they should respond appropriately
Manual Pure-Tone Audiometry
Clinician's Role
Patient Positioning
Never allow them to be in a position to where they can observe your movement
Be aware of your small eye, hand, arm, or body movements because they provide cues.
Positioning depends on the age of the patient
Child: try to stay in their visual field to keep occasional eye contact
Adult: Picks up on more visual cues, so you may need to face their back towards you
Air Conduction Audiometry
Purpose: Specify the amount of a patient's hearing sensitivity at various frequencies
Results can specify the degree of loss
Cannot specify whether the abnormality is conductive, sensorineural or both
Air Conduction Audiometry
Earphones
push back any interfering hair and remove earrings when possible
Remove eyeglass when possible
Supra-aural earphones should be checked for proper placement over the ear canal and to check for a collapsed canal
Can be checked prior to placement of earphones by checking movement of pinna against the head
Insert earphones decrease the need for some of the above
Air Conduction Audiometry
Procedure
Ear selection is only important if patient has a better hearing ear
Most audiologists start with the right ear to keep continuity of testing procedures
Pediatric testing involves switching back and forth between ears to obtain as much information as possible with limited time
Testing begins at 1000Hz and ascends to higher frequencies
Thought to have better test reliability
Most easily heard by the majority of people
Air Conduction Audiometry
Testing usually performed at octave points
Mid Octaves: 750, 1500, 3000, and 6000 Hz; tested when a difference of 20 dB is noted between adjacent octaves
Pure tones may be pulsed automatically or manually or continuous.
Descending and ascending techniques are also employed
Air Conduction Audiometry
ASHA Guidelines
Present tone at 30 dB HL
If no response, raise level to 50 dB HL
Continue to raise in 10 dB steps until the tone is heard
When a response is obtained, lower the tone by 10 dB steps until no response (below threshold)
Raise the tone 5 dB until the response is obtained again.
Repeat process until 50% threshold criterion is met (correctly identify at least 3 out of 6 tone presentations)
The process of stepping down 10 dB and up 5 dB, in order to find the patient's threshold is know as ____________.
Bracketing
Air Conduction Audiometry
Continuous Vs. Pulsed pure tones
Pulsing a tone was tested to have increased awareness by patients
Makes the tone stand out in presence of interfering ear/head noise
Warbled tones (frequency modulated) can aid in patient response
Used when obtaining sound field results to eliminate standing waves
Air Conduction Audiometry
Results are plotted on an audiogram
Pure Tone Average (PTA): 3 frequency (500,1000, 2000Hz) average to help check reliability of testing
Useful for predicting the threshold for speech
Establishes the degree of communication impact imposed by hearing loss
Air Conduction Audiometry
Hearing loss as a percentage
Defining a hearing loss by a percentage negates the concepts of frequency and intensity
May be used by physicians to aid in patient comprehension of hearing loss
Use of percentages ignores audiometric configuration and only looks at the average hearing loss
Audiogram symbol for left ear on audiogram is _______.
X: blue
Audiogram symbol for right ear on audiogram is ______.
O: red
Audiogram symbol for left ear unmasked bone conduction is _____.
>
Audiogram symbol for right ear unmasked bone conduction is ______.
<
Audiogram symbol NR means ________.
No response (to audometer limits)
Audiogram symbol S means _________.
Sound field testing
Audiogram symbol A means __________.
Aided Sound field testing: Hearing aids are in
On an audiogram __________ is shown on the horizontal line and goes from low to high, left to right.
Frequency
On an audiogram __________ is shown on the vertical line and increases from top to bottom.
Intensity
Symbols on the audiogram are plotted after a threshold is obtained under the test frequency and corresponding number (dB HL)
Normal threshold for adults is _____ dB and for kids _____ dB.
25 for adults and 20 for kids
Bone Conduction Audiometry
Purpose: determine the patient’s sensorineural sensitivity
Hearing by BC arises from what 3 phenomenon?
Distortional BC
Inertial BC
Osseotympanic BC
Distortional BC
When the skull is set into vibration, the bones of the skull become distorted, resulting in the distortion of the structures of hearing within the cochlea
This distortion activates certain cells and gives rise to electrochemical activity that is identical to the activity created by an AC signal
Inertial BC
While the skull is moving, the ossicular chain, owning to its inertia, lags behind so that the stapes moves in and out of the oval window
Osseotympanic BC
Oscillation of the skull causes vibrations of the column of air in the outer ear canal
Some of these sound waves escape the ear and some travel the same pathway as would by air conduction
Bone Conduction Audiometry: Placement is usually on the ___________, but can be on the forehead
mastoid process
The mastoid was chosen due to:
BC tones are loudest from the mastoid in normal hearing persons
Due to the mastoid process’s proximity to the ear being tested
Testing procedure is similar to air conduction
Bone Conduction Audiometry
Procedure
Both ears must be uncovered due to an increase in sound intensity when the ear is occluded
This is referred to as the Occlusion Effect (OE) and effects frequencies from 1000 Hz and below
Does not effect conductive hearing losses as much due to the attenuation of sound caused by the hearing loss
Bone Conduction Audiometry
Procedure:
Deciding which ear to test first is unimportant due to cochlea locations
Symbols are plotted on the audiogram in the same fashion as air conduction
Audiogram Interpretation
Results must be looked at for each frequency in terms of:
Amount of hearing loss by AC
Amount of hearing loss by BC
Relationship between AC and BC
Audiogram Interpretation
Conductive Hearing Loss (CHL)
Bone conductive component is within normal limits across all frequencies
Air conduction results show the loss of sensitivity
The difference between the air and bone conduction thresholds is known as the _______.
Air Bone Gap (ABG)
Conductive Hearing Loss Audiogram
These symbols >>>>> appear within normal limits/above these symbols XXXXX, which can be in a downward/upward slope.
Audiogram Interpretation
Sensorineural Hearing Loss
AC results show the total amount of loss
BC results show the amount of SNHL
For a Sensorineural Hearing Loss the Air Bone Gap (ABG) is ___ dB, showing NO conductive involvement.
0-10
Sensorineural Hearing Loss Audiogram
These symbols >>>> appear 0-10 dB above these symbols XXXX anywhere on the audiogram.
Audiogram Interpretation
Mixed Hearing Loss
Air conduction thresholds show a conductive hearing loss
Bone conduction thresholds show a sensorineural hearing loss
For a Mixed Hearing Loss the air bone gap (ABG) shows a conductive component and a gap greater than ___ dB.
10
True or False: Bone Conduction CAN be worse than Air Conduction?
FALSE: Bone Conduction will NEVER be worse than Air Conduction.
Air-Bone Relationships
Hearing by BC is the same by AC in individuals with normal hearing or SNHL
Hearing by AC is poorer than by BC in patients with conductive or mixed hearing losses (some air bone gap)
Hearing by BC poorer than by AC should not occur because both routes ultimately measure the integrity of the sensorineural structures
Tactile Responses
In the presence of severe losses, it is NOT possible to tell whether responses obtained at the highest limits of the audiometer are auditory or tactile
Some patients may feel the vibrations of the BC vibrator due to the intensity of the output signal
Cross Hearing in AC and BC
When hearing sensitivity is significantly better in one ear, the possibility of crossover exists
Sound can escape via AC or BC when the intensity is loud enough to reach the better hearing ear’s threshold
When sounds travel from one side of the heard to the other, a certain amount of energy is lost in transmission, this is known as _______.
Interaural Attenuation (IA)
Interaural Attenuation (IA)
The loss of intensity of a sound introduced to one ear and heard by the other ear
The minimum interaural attenuation (IA) for AC supra-aural earphones is 40 dB
Insert earphones are around 70 dB
Cross Hearing AC and BC
When performing BC testing, it is difficult to know which cochlea is being stimulated, regardless of where the BC oscillator is placed
Crossover is always possible for BC due to the anatomical positioning of the cochleas
The minimum Interaural Attenuation for BC is _ dB.
0: Air-bone gaps over 10 dB are considered significant.
Masking
When vision is being tested, the eye NOT being tested is covered (masked)
For hearing, this is accomplished by delivering a noise to the NONTEST ear to remove it from the test
Masking
When crossover is suspected, the nontest ear must be removed to determine:
If the original responses were obtained through the nontest ear
If they were the nontest ear responses, what are the true thresholds of the test ear
Masking
Masking noise varies depending on the type of testing being performed
Masking of a pure tone is most effective by using frequencies immediately surrounding that pure tone
In regards to masking, the minimum amount of noise required to make a given signal inaudible is referred to as _______.
Effective Masking
In regards to masking, the small shift in threshold of the test ear when masking is introduced into the nontest ear is referred to as __________.
Central Masking
In regards to masking, when the noise is actually so intense in the masked ear that is crosses the skull and masks the test ear it is called ___________.
