AUDIOLOGY. Danielle Billing. Outer Ear The part of the ear that is visible, often called the Pinna, and the ear canal, also called the External Auditory Meatus. Inner Ear The cochlea. The Hearing Mechanism. Middle Ear Consists of the tympanic membrane (eardrum) and the ossicles (bones).
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AUDIOLOGY Danielle Billing
Outer Ear The part of the ear that is visible, often called the Pinna, and the ear canal, also called the External Auditory Meatus Inner Ear The cochlea The Hearing Mechanism Middle Ear Consists of the tympanic membrane (eardrum) and the ossicles (bones) Auditory Nerve The nerve responsible for sending/ receiving auditory information Peripheral Mechanism
The Hearing Mechanism The Brain Responsible for processing and interpreting auditory information Central Mechanism
Outer Ear Inner Ear The Hearing Mechanism Middle Ear Auditory Nerve
The Hearing Mechanism The Brain
Outer Ear Acoustic Energy Inner Ear Hydraulic Energy The Hearing Mechanism Middle Ear Mechanical Energy Auditory Nerve Electrical Energy
Outer Ear Otitis Externa Microtia Anotia Inner Ear Meningitis Noise damage Heredity Common Causes of Hearing Loss Middle Ear Otitis Media Allergies Cholesteotoma Eustachian tube disfunction Mastoiditis Otosclerosis Auditory Nerve Auditory Neuropathy Peripheral Mechanism Conductive Loss Central Mechanism Sensorineural Loss Mixed Loss
Conductive Loss A hearing loss caused by an obstruction or dysfunction of the outer or middle ear Sensorineural Loss A hearing loss caused by a dysfunction in the inner ear (sensori), or the central processing system (neural) Types of Hearing Loss • Mixed Loss • A hearing loss caused by a combination of Conductive and Sensorineural Losses
Degrees of Hearing Loss • Normal 10 or better • Minimal 11-25 d • Mild 26-40 • Moderate 41-55 • Moderately severe 56-70 • Severe 71-90 • Profound greater than 90
Behavioral testing Requires the patient to respond to a stimulus
Introduction to Audiograms: What is an audiogram? • An audiogram is a graphical representation of the hearing thresholds of an individual • These thresholds are determined by the individual’s response to tones presented via earphones or ear inserts (air conduction), or a bone oscillator (bone conduction)
Introduction to Audiograms: the Decibel • Decibel levels of common sounds • 0 dB- The softest sound a person can hear with normal hearing • 10 dB- normal breathing • 20 dB- whispering at 5 feet • 30 dB- soft whisper • 50 dB- rainfall • 60 dB- normal conversation • 110 dB- shouting in ear • 120 dB- thunder
Speech testing • Two basic types: • Speech threshold tests • Speech recognition (supra-threshold) tests
Speech Threshold Testing • Lowest level at which speech can be recognized or detected • SRT- speech recognition threshold • ST- spondee threshold • A spondee is a two-syllable word with each syllable receiving equal emphasis • The patient must correctly identify the speech material presented, typically by repeating the word • The SRT and pure tone average should be within +/- 10 dB of each other
Supra-threshold Speech Testing:Speech Recognition Ability (SRA) • Ability to correctly recognize speech at supra-threshold levels (reported in percentage of correct responses at the intensity level of presentation) • 100% at 70 dB HL • 92% at 50 dB SL
Electroacoustic and Electrophysiological testing Does not require the patient to respond; responses are unconscious and automatic
Ear Canal Volume (ECV) • Provides measure of volume of external ear canal • Volumes greater than 2.5 suggest: • Perforation or • Patent PE tube
Tympanometry • Purpose: to test the function of the tympanic membrane and middle ear • Method: air is added and subtracted from the EAM while a tone is presented • Results presented on a graph called a tympanogram
Tympanometry: Interpreting results • The shape of the tympanogram indicates the functionality of the middle ear
Tympanometry: Interpreting results Type A Type Ad Type As Flaccid tympanic membrane Ossicular disarticulation (broken ossicular chain) Normal Middle Ear Stiff tympanic membrane Otosclerosis Tympanosclerosis
Tympanometry: Interpreting results Type B (low) Type B (high) Type C Non-patent PE tubes Patent PE tubes Negative middle ear pressure
Static Immitance • Definition: the height of the tympanogram at its peak • Helpful in diagnosing middle ear dysfunction • Able to detect small perforations in the tympanic membrane
Static Immittance: Interpreting results Flaccid: disarticulation, flaccid TM, etc. 2.5 Normal .25 Stiff: otosclerosis tympanosclerosis, etc.
Acoustic Reflex Threshold (ART) • “When a sound is of sufficient intensity, it will elicit a reflex of the middle ear musculature” (Stach, 1998, p.270) • The ART measures the threshold a which this reflex of the stapedius muscle occurs • Two types of reflex • Ipsilateral-reflex of the muscle of the stimulated ear- “uncrossed” • Contralateral-reflex of the muscle of the non-stimulated ear- “crossed”
Acoustic Reflex Threshold (ART): Interpreting results • Individuals with normal hearing will have an ART between 70 and 100 dB HL • An elevated or absent response indicates a pathology of the hearing mechanism
Acoustic Reflex Threshold (ART): Interpreting results • An absent contralateral reflex could indicate (when stimulus is presented to the right ear): • Right middle ear disorder • Right severe sensorineural loss • Right acoustic tumor • Brainstem lesion • Left facial nerve disorder • Left middle ear disorder
Auditory Brainstem Response (ABR) • Measures brainstem response to a auditory stimulus • Wave pattern consisting of 5 positive peaks; distance between peaks indicates the amount of time between stimulus and response
Otoacoustic Emissions (OAE) • Measure of the function of the outer hair cells (OHC) of the cochlea • Useful for • Infant screening • Pediatric assessment • Monitoring cochlear function
Put it all together… • By using a combination of behavioral, electroacoustic, and electrophysiological testing through individual analysis and crosschecking, a proper diagnosis and treatment of audiological disorders can occur
The End …or is it?