Audiology Final!!!

Front 1

Applications of Electroacoustic and Electophysiologic Measures

Back 1

- used to test middle and inner ear function
-substantiate/augment results from basic audiologic tests
-determine whether lesions are present in retrocochlear pathway (tumor, prob with 8th nerve)
-Aid in diagnosis of an auditory disorder previously undetected

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Why use these tests? Who should get them?

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These assessments are objective. Don't need clients participation. Can be used for neonates, young children, or non-verbal, low functioning adults.

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Tests of Electroacoustic Measures

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Immittance Audiometry:
-Static Acoustic compliance (admittance)-flow of energy through TM
-Tympanometry- tests mobility of TM
-Acoustic reflex- sensitivity and motor movement of stapedius muscle

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Admittance
Impedance

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Admittance: Total energy flow through a system (hose!)
Impedance: Total opposition to energy flow (kink in hose!)
*Admittance and Impedance are inversely related!

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Reactance

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Combination of admittance and impedance.
Combination of mass and stiffness.
As frequency increases, important of mass also increases; as frequency decreases, importance of stiffness increases.
*low f- mass dominated system (more energy needed to move ossicles, TM)
high f- stiffness dominated system

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Immittance

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Immittance:Term that refers to either impedance data or admittance. A measure of how readily a system can be set in to vibration from a driving force. A physical measure. The flow of energy and how much flow is impeded by energy.
-Ear is largely a stiffness dominated system
-Immittance is NOT a physical quantity (measurement)

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Biologic contributions to Immittance

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Resistance- determined primarily by ligaments that support ossicles
Mass- determined primarily by weight of ossicles and TM
Stiffness- determined primarily by the load of fluid pressure from inner ear
*Normally functioning ME is air filled, fluid creates stiffness

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Middle-ear Immittance Audiometry

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-A way of assessing the manner in which energy flows through the outer and middle ears to the cochlea. (How much pressure needs to be added to the system?)
-An objective test (behavioral responses not needed)
-measured by delivering pure tone signal of constant sound pressure (tone stiffens system, air pressure added)
-any change in intensity is noted as change of energy flow through ME
*Objective- how much pressure is needed to move the ear drum?

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Clinical Applications: Immittance Audiometry

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-Sensitive in detecting disorders of ME
-useful in differentiating cochlear from retrocochlear disorders (looks at brainstem)
-helpful in estimating degree of peripheral sensitivity
-cross check of pure tone audiometry

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Middle Ear Analyzer

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-sees how much energy it takes to push TM in/out/midline
-"peak" is midpoint, tells us amount of pressure needed
-delivers low f tone
manometer- measures amount or air pressure being introduced in to system

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Static Acoustic Compliance

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- isolated contribution of middle ear to over all acoustic immittance
-measures ease of flow of acoustic energy through middle ear
-measured cubic cm
-"the overall hight of the tympanogram at it's peak"

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Tympanometry

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-measurement of mobility of middle ear when air pressure is varied from +200 to -400 daPa
-normal peak pressure between -100 and +100
-compliance between 0.3cm3 -1.7cm3

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Acoustic Reflexes

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-bilateral contraction of stapedius muscles in response to high intensity sound
-notmal thresholds around 70-100 dbHL
-measures what happens in multiple systems (brainstem as well)
-measures intensity in which stapedius contracts
*contralateral- happens in both ears
*acoustic reflex exceedingly sensitive to ME disorder

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Auditory Evoked Potentials (AEP's)

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-measures acoustic stimulation by electrical voltage in brain
-auditory "EEG's", electrodes on scalp
-assessment of central auditory nervous system
- can predict hearing sensitivity in individuals hard to test; neonates, ADD, etc
*APD- will get abnormal results because of poor auditory processing connection

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AEP Categories; 5 categories based on latencies (amount of time)

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Electrocochleography (ECoG)
-with in first 5 ms after signal onset
-activity of cochlea and CN IIIV
Auditory brainstem response (ABR)
-most common
-with in first 10 ms
-neural activity from CNIIIV to midbrain
Middle latency response (MLR)
-first 50 ms
-thalmus activity
Late latency response (LLR)
-50-200 ms
-primary auditory cortex
Auditory event-related potential
-250 ms
-primary auditory cortex
* past 250 ms, no longer an auditory event, but cranial event

Front 16

Otoacoustic Emissions (OAE's)

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Sounds produced by cochlea. Usually evoked by auditory stimulus but can occur spontaneously. Considered an outer hair cell phenomenon.
-frequency specific, low intensity sounds
-measures function of outer hair cells

*Outer hair cells- tuned specifically to intensity, first line in knowing sound has occurred, greater in # then inner hair cells

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Types of Otoacoustic Emissions

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Spontaneous- occur with out any introduction of signal.
Evoked- occur during and after presentation of stimulus
Transient (TE)- elicited via click. TIMING information.
Distortion-product (DP)- elicited via tones. FREQUENCY information.

Front 18

Clinical Applications: OAE's

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Infant Hearing Screening
-quick and easy
Pediatric assessment
-can be obtained even with difficult child
Cochlear functioning monitoring
-for patients undergoing oxotoxic medical treatments
Diagnostic applications
-retrocochlear/neurological disorders (tumors)
-evaluation of "functional" hearing loss
-

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Hearing Aid's

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-for over 90% of all types of HL, hearing aids are the only treatment option
-only 20% of adults who need hearing aids, actually have them

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A good candidate for amplification...

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-acceptance of hearing loss
-mild-moderately severe sensorineural hearing loss (enough residual hearing remaining to amplify)
-MOTIVATION
-communication problems: at home, work, socially. Avoids certain situation, activities because can't hear.
-encouragement from spouse/ significant other (don't blame)

Front 21

Disability vs Handicap

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Disability- loss of function. The actual problem.

Handicap- the psychological disadvantages which result from hearing loss (or other disability)

Front 22

Benefits from Amplification

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Benefit and need for amplification equal until 86-100 dbHL, when cochlear implants a better option
2 hearing aids more beneficial then one:
-provide fuller sound quality (stereo vs mono)
-lesson backround noise
-enable volume levels to be set lower, minimizing risk of sound distortion
-easier to hear soft sounds

Front 23

Amplification Devices Used

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HEARING AIDS
CROS HA- "cross aids", amplifier and receiver w wire
CIC-completely in the canal
ITC- in the canal
ITE- in the ear
BTE- behind the ear (slim tube or traditional)
ASSISTIVE LISTENING DEVICES
-Auditory devices (FM system, TV ears)
-nonauditory devices (shaking alarm clock)
-classroom amplification (FM systems)
IMPLANTABLE DEVICES
-Baha
-Cochlear implants

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How Hearing Aid's Work

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Sound entry (input)
-sound waves enter microphone
-microphone converts the acoustic signal (speech) in to an electrical signal
Processing
-digital signal processor processes/manipulates sound
Sound exit (output)
-receiver converts electrical signal back to acoustic
-amplified sound enters the ear
-

Front 25

Hearing Aid Components

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Microphone
Amplifier
Receiver
Controls (battery hatch, volume control)

Front 26

2 main Classifications of Hearing Aids

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Custom: built for individual through impression of ear. Fit's entirely within pinna and ear canal.

BTE- fit behind pinna and connect to a sound tube and earpiece with routes amplified sound in to ear.

*new cosmetically appealing styles (neither category)
Lyric: extended wear hearing aid. Fit's deeply in ear canal and worn up to 3 mo without removal.
SoundBite: bone conduction hearing system that transmits sound via teeth.

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Behind The Ear Styles

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Conventional BTE-:all types of hearing loss

"Slim tube" BTE- solely for high f loss, very small, barely noticeable, reduces "plugged up" feeling

RIC- receiver in canal BTE- speaker or receiver is moved from instruments housing in to ear tip. Smaller and more cosmetically appealing.

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Custom Hearing Aid Styles

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ITE
-sits entirely in outer ear
-mild-moderately sever HL
-allows for widest selection of features
ITC
-sits within bottom portion of outer ear
-mild-moderate HL
-additional features available, but not as many as ITE
*NOT good for users with TMJ
CIC
-deep within ear canal, virtually invisable
-mild to moderate HL
-requires good dexterity to insert, remove
-can be effected by conditions in ear canal (wax)

Front 29

Evolution of Hearing Aid Technology

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-first were analogue, linear
-maturation brought smaller units
-non linear came next
-1990's- digital hearing aids, greater control!
-2000's new signal processing strategies
*now blue tooth enabled!

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Electroacoustic Characteristics of Hearing Aids

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Output sound pressure level (OSPL): maximum sound pressure level that can be produced. Limits intensity to avoid damage.
Input/Output (I/O) function: whatever enters mic is output for reciever
Gain: amouny of amplification provided by which output level exceeds input level (dB SPL)
Compression: Imput, output, wide dynamic range (WDRC)
WDRC: Wide dynamic range compression. Makes sure loud sounds are in dynamic range. Amplifies soft sounds more then loud sounds.
*Peak clipping- distortion of sound

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Digital Sound Processing (DSP) features...

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Automatic sound processing
-softer sounds given more amplification then louder
-amplification doesn't get in the way of needed loud sounds (fricatives)
Directional microphone systems
-two mics used to improve speech understanding
Noise reduction
-reduce background noise
Feedback cancellation
Multiple listening programs
-set for specific environments
Wireless Technology
-enable binaural instruments to communicate/synchronize with each other and other devices
Self-Learning technology
-"learns" patient listening preferences over time

Front 32

Other features commonly found in HA's

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Telecoil: alternate input source via magnetic signal. Wire around magnet, improves amplification by using magnetic fields from other sources.

Direct Audio Input: alternate input source, listens to electrical signal instead of (or in addition to) target
sound.

*magnetic/electrical signal can be from telephone, TV,
etc

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Amplification factors to consider...

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-how much amplification (gain) needed?
-does this patient have good speech recognition? (audiometric considerations)
-lifestyle
-fine motor skills (dexterity)
-cost
*best HA for patient are ones they will wear!

Front 34

Hearing Aid Patient Controls

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-On/off switch
-volume control
-MTO switch (M: microphone, T: telecoil, O: off)
-programmable controls

Front 35

Assistive Listening Devices- 3 types

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Auditory Devices
-personal amplifiers
-TV listening (closed captioning)
Nonauditory Devices
-alarm clocks (shaking)
-TTY (amplified telephone)
Classroom amplification
-FM wireless system (coupled to childs ear)
-hard wire system
-infrared system
-sound field amplification (transmitted directly to wearer)

Front 36

Non-implantable devices/Implantable devices

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Non implantable devices
-Lyric
-Sound bite (Sonitus)
Implantable Devices
-Bone-anchored (osseointegrated) amplification
-Cochlear implants
*devices should not be implanted on children younger then 12 mo

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Baha/ Cochlear implant

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-implanted on mastoid process
-conductive HL
-good for patients with microtia, atresia (can't insert) -
-not appropriate for children under 8 yrs
Cochlear implant
-through round window, threaded through cochlea
-processor, headpiece, implant, electrodes

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3 Main Challanges in Pediatric Audiology

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1) To identify as early as possible those children who are at risk for HL and need further evaluation (screening). Begins (often) at birth with OAE's.
2)To determine if those children ID'd actually have HL. (Can fail screening, but pass diagnostic.)
3) To identify the nature/quantify the extent of suprathreshold sensitivity in children suspected of having an APD. (Academic implications.)

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Newborn/Infant Screening

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-HL the most common congenital condition in US.
-infant/newborn screening now mandated in US.
-to ID infants who are at risk for significant sensorinueral HL and require further testing

Front 40

Risk Factors...

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-family history of childhood HL
-congenital infections
-craniofacial abnormalities
-low firth weight (can't fight off infections)
-hyperbilirubinemia
-asphyxia
-ototoxic meds
-bacterial meningitis
-asphyxia
-mechanical ventilation over 5 days
-syndromes which include HL
Prenatal,/postnatal
(S)TORCH- infections of syphilis, taxoplasmosis, other, rubella, cytomegalovirus, herpes

Front 41

Screening

Back 41

Screening- test designated to separate persons who have a disorder from those who do not
Screening tests must be:
-simple, safe, rapid, cost effective , enable early ID of disorder, offer subsequent intervention
- Screening done at 1 month, at 3 months specify disorder, at 6 months remediate (intervene)

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Why screen? Determining factors-

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-importance of disorder
-ability to reach those who could benefit
-prevalent
-acceptably diagnosed
-availability of diagnostic/treatment recourses (follow ups)
-availability of cost effective programs

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Evaluating a Screening Test

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Screening evaluated against a "gold standard" for...
-sensitivity: percentage of time a test correctly identifies a site of lesion
-specificity: percentage of time a test correctly rejects an incorrect diagnosis
-pass/fail criteria
-prevalence
-predictive value: the percentage of all positive test results that are truly positive and the percentage of all negative results that are truly negative

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Newborn Hearing Screening: 3 pronged assessment procedure

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1. Automatic auditory brainstem response (CN VIII as determined by wave V - measured through clicks. Uses 4 electrodes)

2. Otoacoustic emissions (measures OHC)

3. Immittance (Tympanometry) - tests ME to see if it’s intact/right amount of immittance

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Pediatric Audiology: Goals of audiometric evaluation

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-to identify existence of an auditory disorder
-to identify nature of disorder
-to identify nature and extent of the hearing impairment caused by the disorder

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Pediatric Screening

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- We need more of it! Only 3% aged 6 months-11 yrs receive screening at primary health care source
- School based: most use pure tone, but that doesn’t give full picture. Should be used in conjunction w immittance

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Reasons for Audiologic consultation

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-The child who has already undergone some sort of screening/is at risk for hearing impairment
-speech and/or language not progressing in normal fashion
-presence of an otologic disease
-failed hearing screening (newborn, school)
-suspected auditory processing disorder

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Testing Strategies: Behavioral Assessments O-2 yrs

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Behavioral Assessments: 0-2 yrs
- Behavioral Observation Audiometry (BOA): 0-6mo
-Visual Reinforcement Audiometry (VRA) : 6-24 mo

Behavioral Assessments: 2-5 yrs
-Conditioned Play Audiometry (CPA)

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Behavioral Observation Audiometry

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Behavioral Observation Audiometry (BOA): 0-6mo
-birth to 6 mo
-introduce warble tone and speech stimuli
-observe infants response to signals (typical responses include increase/decrease of sucking action, movement)
-does NOT provide ear specific information
-thresholds marked with "s" if soundfield used, earphones not recommended
-used in conjunction with immittance and otoacoustic emissions audiometry (OEA) to gain more complete picture of hearing status
Visual Reinforcement Audiometry:
-

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Visual Reinforcement Audiometry

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- 6 months to 24 months
-audiometric technique in which the child's behavioral response to a sound is conditioned by reinforcement of visual stimuli
-typical responses include head turn/tilt towards sound source
- Similar to BOA, but behavior is reinforced w a treat
- Can be in soundfield (NO ear specific info provided)
- Can be in headphones (YES ear specific info provided)
- Warble tones (soundfield), speech (child's name, body parts), pure tones (if using headphones)
- Child must be carefully conditioned
-immittance and OAE used in conjunction with VRA to provide complete picture of hearing status

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Conditioned Play Audiometry (CPA)

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- 2-5 yrs
- Audiometric technique in which child is conditioned to respond to a stimulus by engaging in some game (e.g. drop a block in a bucket for a positive response)
- Use spondees
-Ear specific information provided using headphones
-Both pure tone and speech stimuli used to elicit responses
-Immitance and otoacoustic emissions audiometry used in conjunction with CPA to provide complete picture of hearing status

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School Based (?) Screening Programs: Equipment/tests

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-Audioscope: hand held otoscope with built in audiometer. Delivers 25 or 40 dbHL tones for speech frequencies (500, 1000, 2000, 4000)
-Acoustic reflectometry : tests ME. Non invasive.
-Hand held Typmanometers: small, portable hand held immitance screening device. Significant potential! Additional research needed.

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School Based Screening: Who should be screened?

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-Most programs focus on nursery school aged through grade 3
-After 3rd grade, should be screened in 3-4 yr intervals
-Other groups include children with preexisting HL, multiple handicaps, delayed language, ear infections

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Follow up Programs for Children (who fail screening)

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Screening of little value if follow up not provided.
- Noncompliance: Principal problem in newborn screening. Parents don't bring kids back.
- For preschool and school-age programs, screening coordinator responsible for follow up. (Should be given comprehensive audiologic test with in few days of failed test. Letter should be sent, parents informed.)
- Parent counseling- essential in follow up
- Referral to educational services that will be used for planning and placement

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(Central) Auditory Processing Disorders

ASHA STATEMENT

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"APD is an impairment of various aspects of human auditory perception, including temporal, spectral, and binaural hearing, and ordering, and grouping of sounds".

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APD is best described as...

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An impaired ability to process acoustic information that cannot be attributed to impaired hearing sensitivity, impaired language, or impaired intellectual function.

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What is (C)APD?

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What is (C)APD?
-an auditory disorder that results from deficits in central auditory nervous system function and/or interactions of disorders at both peripheral and central sights without necessarily attributing difficulties to a single anatomic locality.
-”What we do with what we hear”

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Features of (C) APD

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-usually does not result from documented neuropathic conditions
-presents as communication disorders that resemble hearing impairment
-Effective use of audition is impeded by more than the detrimental effects expected from peripheral pathology alone
-Modality specific (ie auditory input)
-No biologic marker (cannot be identified objectively)
-CANS dysfunction usually idiopathic and is not ear specific
-It is NOT considered to be a receptive language processing/neuropsychological disorder
-estimated in 2-3% of children, twice as likely in boys

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Signs of APD...

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-poor listening skills
-short attention spans
-poor memory and reading comprehension
-difficulty in linguistic sequencing
-problems learning to read and spell
*problems with detection, discrimination, identification, comprehension

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Heirarchy of Auditory Skills

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-Auditory detection: the first essential step in the process of spoken language processing.
-Auditory discrimination: the ability to determine if two sounds are the same or different.
-Identification: the ability to repeat what has been heard or select a word from a group of choices.
-supported by good vocabulary and language base
-Comprehension: processing and appropriate response to spoken language.

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How is APD characterized?

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Reduced ability to...
-understand in backround noise
-understand speech of reduced redundancy
-localize and lateralize sound stimuli
-precess normal or altered temporal (sequence) cues
Inconsistent response to auditory stimuli
Demonstrates a relatively short attention span and/or becomes easily fatigued when confronted with long/complex listening tasks

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APD characterization cont...

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-Appearing overly distracted by both auditory and visual stimuli
-Frequent requests for repetition of verbal information
-Problems with short and long term memory skills
-Difficulty attending to speech in the presence of background noises
-Difficulties hearing the differences in sounds and words

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Populations Diagnosed with (C)APD

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Children
-interferes with educational input (child cannot listen as fast as teacher is talking)
-may coexist with disorders of language, attention, and/or learning (ADD)
Elderly/Adults
-Phonemic regression: changes in structure and function of both peripheral and central auditory nervous system contribute to distorted acoustic input

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Controversies surrounding APD

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-(Central) Auditory Processing Disorder vs Auditory Processing Disorder
-Top down vs bottom up processing of auditory info
-Test battery used for diagnoses
-Multidisciplinary approach for diagnosis/remediation

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Assessment and Diagnosis of (C)APD

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Relies on operational definitions
-results of speech auditometry and other behavioral measures

Typically the child is:
-less than (greater than?) 7 yrs
-normal IQ
-english as first language
-normal peripheral hearing
*Multidisciplinary approach to diagnosis and assessment provides most complete picture (Audiologist, SLP, Psychologist, etc)

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Role of Audiologist in (C)APD Assessment

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*When client at risk, SLP refers to audiologist
-complete audiometric evaluation to rule out HL
-(C)APD test battery (linguistic and non linguistic stimuli)
-filtered speech
-speech in noise test
-dichotic tests (words, sentences)
-phonemic awareness
-frequency patterns
-duration patterns
-gap detection

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Role of SLP in Remediation

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Auditory training
-awareness/attention
-discrimination
-speech-in-noise
-memory
-metalinguistic/metacognitive training
Popular programs used by SLP's
-Fast ForWord
-Earobics
-Lindamood-Bell

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Role of Audiologist in Remediation

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Amplification
-FM Systems: work to reduce reverberation time, background noise, distance between student and teacher, improve signal-to-noice ratio